diff --git a/Pages/Export/CalendarExportDisplay.php b/Pages/Export/CalendarExportDisplay.php
index b592b15e3..20c18961a 100644
--- a/Pages/Export/CalendarExportDisplay.php
+++ b/Pages/Export/CalendarExportDisplay.php
@@ -1,5 +1,6 @@
 <?php
 
+use LibreBooking\Calendar\IcsMethod;
 use Sabre\VObject\Component\VAlarm;
 use Sabre\VObject\Component\VCalendar;
 use Sabre\VObject\Component\VEvent;
@@ -18,14 +19,16 @@ public function __construct()
     /**
      * @param iCalendarReservationView[] $reservations
      * @param string|null $calendarName Optional display name rendered as X-WR-CALNAME
+     * @param IcsMethod $method PUBLISH for feeds and exports. Emails send REQUEST, or CANCEL for deletions,
+     *                          with the default address as organizer and the recipient as the only attendee.
      */
-    public function Render(array $reservations, ?string $calendarName = null): string
+    public function Render(array $reservations, ?string $calendarName = null, IcsMethod $method = IcsMethod::PUBLISH): string
     {
         // Values passed as constructor children are merged over getDefaults(),
         // replacing the PRODID that VCalendar would otherwise generate.
         $vcal = new VCalendar([
             'PRODID' => '-//LibreBooking//NONSGML ' . Configuration::VERSION . '//EN',
-            'METHOD' => 'REQUEST',
+            'METHOD' => $method->value,
         ]);
 
         if ($calendarName !== null && $calendarName !== '') {
@@ -54,10 +57,18 @@ public function Render(array $reservations, ?string $calendarName = null): strin
             $event->add('DTEND', $res->DateEnd->Format($isoFormat));
             $event->add('LAST-MODIFIED', $res->LastModified->Format($isoFormat));
             $event->add('LOCATION', $res->Location);
-            $event->add('ORGANIZER', 'mailto:' . $res->OrganizerEmail, ['CN' => $res->Organizer]);
-            $event->add('STATUS', $res->IsPending ? 'TENTATIVE' : 'CONFIRMED');
+            if ($method !== IcsMethod::PUBLISH && !empty($res->OrganizerSentBy)) {
+                $event->add('ORGANIZER', 'mailto:' . $res->OrganizerSentBy, ['CN' => $res->SenderName]);
+            } elseif (!empty($res->OrganizerEmail)) {
+                $organizerParams = ['CN' => $res->Organizer];
+                if (!empty($res->OrganizerSentBy)) {
+                    // RFC 5545 §3.2.18: the site's address sends on the owner's behalf
+                    $organizerParams['SENT-BY'] = 'mailto:' . $res->OrganizerSentBy;
+                }
+                $event->add('ORGANIZER', 'mailto:' . $res->OrganizerEmail, $organizerParams);
+            }
+            $event->add('STATUS', $method === IcsMethod::CANCEL ? 'CANCELLED' : ($res->IsPending ? 'TENTATIVE' : 'CONFIRMED'));
             $event->add('SUMMARY', $res->Summary);
-            $event->add('SEQUENCE', 0);
             $event->add('URL', $res->ReservationUrl);
             $event->add('X-MICROSOFT-CDO-BUSYSTATUS', 'BUSY');
 
@@ -88,6 +99,17 @@ public function Render(array $reservations, ?string $calendarName = null): strin
                 }
             }
 
+            $attendeeEmail = $res->AttendeeEmail ?? $res->OrganizerEmail;
+            if ($method !== IcsMethod::PUBLISH && !empty($res->OrganizerSentBy) && !empty($attendeeEmail)) {
+                $attendeeName = $res->AttendeeEmail ? $res->AttendeeName : $res->Organizer;
+                $event->add('ATTENDEE', 'mailto:' . $attendeeEmail, array_filter([
+                    'CN' => $attendeeName,
+                    'ROLE' => 'REQ-PARTICIPANT',
+                    'PARTSTAT' => 'NEEDS-ACTION',
+                    'RSVP' => 'FALSE',
+                ]));
+            }
+
             if ($res->StartReminder !== null) {
                 $alarm = new VAlarm($vcal, 'VALARM');
                 $event->add($alarm);
diff --git a/lib/Application/Schedule/iCalendarReservationView.php b/lib/Application/Schedule/iCalendarReservationView.php
index 8f6470d11..a28ab2e78 100644
--- a/lib/Application/Schedule/iCalendarReservationView.php
+++ b/lib/Application/Schedule/iCalendarReservationView.php
@@ -9,6 +9,10 @@ class iCalendarReservationView
     public $Description;
     public $Organizer;
     public $OrganizerEmail;
+    public $OrganizerSentBy;
+    public $SenderName;
+    public $AttendeeName;
+    public $AttendeeEmail;
     public $RecurRule;
     public $ReferenceNumber;
     public $Summary;
@@ -60,12 +64,6 @@ public function __construct($res, UserSession $currentUser, IPrivacyFilter $priv
         $this->ExportFactory = PluginManager::Instance()->LoadExport();
 
         $privateNotice = 'Private';
-        $privateEmail = Configuration::Instance()->GetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS);
-        static $missingPrivateOrganizerEmailLogged = false;
-        if (!$canViewUser && $privateEmail === '' && !$missingPrivateOrganizerEmailLogged) {
-            Log::Error('ICS private organizer email is not configured. Set the email.default.from.address setting.');
-            $missingPrivateOrganizerEmailLogged = true;
-        }
 
         $this->Classification = method_exists($this->ExportFactory, 'GetIcalendarClassification') ? $this->ExportFactory->GetIcalendarClassification($res) : 'PUBLIC';
         if ($res->DateCreated) {
@@ -78,9 +76,23 @@ public function __construct($res, UserSession $currentUser, IPrivacyFilter $priv
         $this->DateStart = $res->StartDate;
         $this->Summary = $canViewDetails ? $factory->Format($res, $summaryFormat) : $privateNotice;
         $this->Description = $canViewDetails ? ($res->Description ?? '') : $privateNotice;
-        $fullName = new FullName($res->OwnerFirstName, $res->OwnerLastName);
-        $this->Organizer = $canViewUser ? $fullName->__toString() : $privateNotice;
-        $this->OrganizerEmail = $canViewUser ? $res->OwnerEmailAddress : $privateEmail;
+
+        $defaultFromAddress = Configuration::Instance()->GetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS);
+        if ($canViewUser) {
+            $ownerName = new FullName($res->OwnerFirstName, $res->OwnerLastName);
+            $this->Organizer = $ownerName->__toString();
+            $this->OrganizerEmail = $res->OwnerEmailAddress;
+            $this->OrganizerSentBy = $defaultFromAddress;
+            $this->SenderName = Configuration::Instance()->GetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME);
+        } else {
+            $this->Organizer = $privateNotice;
+            $this->OrganizerEmail = $defaultFromAddress;
+            static $missingPrivateOrganizerEmailLogged = false;
+            if ($defaultFromAddress === '' && !$missingPrivateOrganizerEmailLogged) {
+                Log::Error('ICS private organizer email is not configured. Set the email.default.from.address setting.');
+                $missingPrivateOrganizerEmailLogged = true;
+            }
+        }
         $this->RecurRule = $this->CreateRecurRule($res);
         $this->ReferenceNumber = $res->ReferenceNumber;
         $this->ReservationUrl = sprintf(
@@ -97,10 +109,6 @@ public function __construct($res, UserSession $currentUser, IPrivacyFilter $priv
         $this->LastModified = empty($res->ModifiedDate) || $res->ModifiedDate->ToString() == '' ? $this->DateCreated : $res->ModifiedDate;
         $this->IsPending = $res->RequiresApproval;
 
-        if ($canViewUser && $res->OwnerId == $currentUser->UserId) {
-            $this->OrganizerEmail = str_replace('@', '-noreply@', $res->OwnerEmailAddress);
-        }
-
         $this->ExtraIcalLines = method_exists($this->ExportFactory, 'GetIcalendarExtraLines') ? $this->ExportFactory->GetIcalendarExtraLines($res) : null;
     }
 
diff --git a/lib/Email/IEmailMessage.php b/lib/Email/IEmailMessage.php
index b3e6f3f01..11c985b5a 100644
--- a/lib/Email/IEmailMessage.php
+++ b/lib/Email/IEmailMessage.php
@@ -46,7 +46,7 @@ public function ReplyTo();
      * @abstract
      * @param string $contents
      * @param string $fileName
-     * @param string|null $mimeType Full Content-Type value (e.g. 'text/calendar; method=REQUEST'). Null auto-detects from $fileName.
+     * @param string|null $mimeType Full Content-Type value (e.g. 'text/calendar; method=PUBLISH'). Null auto-detects from $fileName.
      */
     public function AddStringAttachment($contents, $fileName, ?string $mimeType = null);
 
diff --git a/lib/Email/Messages/ReservationDeletedEmail.php b/lib/Email/Messages/ReservationDeletedEmail.php
index 83c9f513f..93f13205e 100644
--- a/lib/Email/Messages/ReservationDeletedEmail.php
+++ b/lib/Email/Messages/ReservationDeletedEmail.php
@@ -1,5 +1,7 @@
 <?php
 
+use LibreBooking\Calendar\IcsMethod;
+
 require_once(ROOT_DIR . 'lib/Email/Messages/ReservationEmailMessage.php');
 
 class ReservationDeletedEmail extends ReservationEmailMessage
@@ -25,4 +27,9 @@ protected function GetTemplateName()
     {
         return 'ReservationDeleted.tpl';
     }
+
+    protected function GetIcsMethod(): IcsMethod
+    {
+        return IcsMethod::CANCEL;
+    }
 }
diff --git a/lib/Email/Messages/ReservationEmailMessage.php b/lib/Email/Messages/ReservationEmailMessage.php
index 3fb8df66d..0fafb94d8 100644
--- a/lib/Email/Messages/ReservationEmailMessage.php
+++ b/lib/Email/Messages/ReservationEmailMessage.php
@@ -1,5 +1,7 @@
 <?php
 
+use LibreBooking\Calendar\IcsMethod;
+
 require_once(ROOT_DIR . 'lib/Email/namespace.php');
 require_once(ROOT_DIR . 'Pages/Pages.php');
 require_once(ROOT_DIR . 'Pages/Export/CalendarExportDisplay.php');
@@ -215,14 +217,33 @@ protected function PopulateIcsAttachment($currentInstance, $attributeValues)
         $rv->UserPreferences = $this->reservationOwner->GetPreferences();
         $rv->OwnerEmailAddress = $this->reservationOwner->EmailAddress();
 
-        $icsView = new iCalendarReservationView($rv, $this->reservationSeries->BookedBy(), new NullPrivacyFilter());
+        // BookedBy() is null for series from ReservationRepository::BuildSeries(); use the
+        // owner, with a timezone for the {startdate}/{enddate} summary placeholders.
+        $currentUser = $this->reservationSeries->BookedBy();
+        if ($currentUser === null) {
+            $currentUser = new UserSession($this->reservationOwner->Id());
+            $currentUser->Timezone = $this->timezone;
+        }
+        $icsView = new iCalendarReservationView($rv, $currentUser, new NullPrivacyFilter());
+        // the attendee is whoever the email goes to: the owner, or an invitee, guest or share recipient
+        $recipient = $this->To();
+        $recipient = is_array($recipient) ? $recipient[0] : $recipient;
+        $icsView->AttendeeName = $recipient->Name();
+        $icsView->AttendeeEmail = $recipient->Address();
+
+        $method = $this->GetIcsMethod();
 
         $display = new CalendarExportDisplay();
-        $icsContents = $display->Render([$icsView]);
+        $icsContents = $display->Render([$icsView], null, $method);
         $this->AddStringAttachment(
             contents: $icsContents,
             fileName: 'reservation.ics',
-            mimeType: 'text/calendar; charset=UTF-8; method=REQUEST'
+            mimeType: "text/calendar; charset=UTF-8; method={$method->value}"
         );
     }
+
+    protected function GetIcsMethod(): IcsMethod
+    {
+        return IcsMethod::REQUEST;
+    }
 }
diff --git a/lib/Email/Messages/ReservationUpdatedEmail.php b/lib/Email/Messages/ReservationUpdatedEmail.php
index c9951053b..640f9d770 100644
--- a/lib/Email/Messages/ReservationUpdatedEmail.php
+++ b/lib/Email/Messages/ReservationUpdatedEmail.php
@@ -6,7 +6,7 @@ class ReservationUpdatedEmail extends ReservationEmailMessage
 {
     public function Subject()
     {
-        return $this->Translate('ReservationUpdatedAdminSubjectWithResource', [$this->primaryResource->GetName()]);
+        return $this->Translate('ReservationUpdatedSubjectWithResource', [$this->primaryResource->GetName()]);
     }
 
     protected function GetTemplateName()
diff --git a/src/Calendar/IcsMethod.php b/src/Calendar/IcsMethod.php
new file mode 100644
index 000000000..f893cb075
--- /dev/null
+++ b/src/Calendar/IcsMethod.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LibreBooking\Calendar;
+
+/**
+ * RFC 5546 iTip method for an ICS VCALENDAR.
+ */
+enum IcsMethod: string
+{
+    case PUBLISH = 'PUBLISH';
+    case REQUEST = 'REQUEST';
+    case CANCEL = 'CANCEL';
+}
diff --git a/tests/Presenters/CalendarExportPresenterTest.php b/tests/Presenters/CalendarExportPresenterTest.php
index 95afec989..0febede7e 100644
--- a/tests/Presenters/CalendarExportPresenterTest.php
+++ b/tests/Presenters/CalendarExportPresenterTest.php
@@ -2,6 +2,8 @@
 
 declare(strict_types=1);
 
+use LibreBooking\Calendar\IcsMethod;
+
 require_once(ROOT_DIR . 'Pages/Export/CalendarExportPage.php');
 require_once(ROOT_DIR . 'Presenters/CalendarExportPresenter.php');
 
@@ -94,25 +96,30 @@ public function testCannotSeeReservationDetailsIfConfiguredOff()
         $this->presenter->PageLoad($this->fakeUser);
     }
 
-    public function testOrganizerIsOwnerIfCurrentUserIsNotOrganizer()
+    public function testOrganizerIsTheReservationOwnerWithSentByAsTheConfiguredDefaultAddress()
     {
-        // this fixes a bug in outlook which prevents you from adding a meeting that you are the organizer of
+        // ORGANIZER is the owner; SENT-BY is the site's default address.
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'bookings@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'Example Bookings');
+
         $user = new FakeUserSession();
         $res = new ReservationItemView();
-        $res->OwnerId = $user->UserId + 1;
+        $res->OwnerId = $user->UserId;
         $res->OwnerFirstName = 'f';
         $res->OwnerLastName = 'l';
         $res->OwnerEmailAddress = 'e@m.com';
 
         $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter);
-        $this->assertEquals($res->OwnerEmailAddress, $reservationView->OrganizerEmail);
-        $fullName = new FullName($res->OwnerFirstName, $res->OwnerLastName);
-        $this->assertEquals($fullName->__toString(), $reservationView->Organizer);
+        $this->assertEquals('e@m.com', $reservationView->OrganizerEmail);
+        $this->assertEquals('f l', $reservationView->Organizer);
+        $this->assertEquals('bookings@example.com', $reservationView->OrganizerSentBy);
     }
 
-    public function testOrganizerIsDefaultedIfCurrentUserIsOrganizer()
+    public function testOrganizerFallsBackToTheDefaultAddressWithNoSentByWhenPrivacyHidesTheOwner()
     {
-        // this fixes a bug in outlook which prevents you from adding a meeting that you are the organizer of
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'bookings@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'Example Bookings');
+
         $user = new FakeUserSession();
         $res = new ReservationItemView();
         $res->OwnerId = $user->UserId;
@@ -120,10 +127,55 @@ public function testOrganizerIsDefaultedIfCurrentUserIsOrganizer()
         $res->OwnerLastName = 'l';
         $res->OwnerEmailAddress = 'e@m.com';
 
+        $this->privacyFilter->_CanViewUser = false;
+        $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter);
+
+        $this->assertEquals('bookings@example.com', $reservationView->OrganizerEmail);
+        $this->assertEquals('Private', $reservationView->Organizer);
+        // no real identity, so nothing to send on behalf of
+        $this->assertNull($reservationView->OrganizerSentBy);
+    }
+
+    public function testOrganizerIsOmittedFromRenderedOutputWhenOwnerHasNoEmailOnFile()
+    {
+        // an owner without an email gets no ORGANIZER rather than an empty "mailto:"
+        $user = new FakeUserSession();
+        $res = new ReservationItemView();
+        $res->StartDate = Date::Now();
+        $res->EndDate = Date::Now()->AddHours(1);
+
         $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter);
-        $this->assertEquals('e-noreply@m.com', $reservationView->OrganizerEmail);
-        $fullName = new FullName($res->OwnerFirstName, $res->OwnerLastName);
-        $this->assertEquals($fullName->__toString(), $reservationView->Organizer);
+        $this->fakeConfig->_ScriptUrl = 'https://example.com/Web';
+        $display = new CalendarExportDisplay();
+        $ics = $display->Render([$reservationView]);
+
+        $this->assertStringNotContainsString('ORGANIZER', $ics);
+    }
+
+    public function testOrganizerRendersWithSentByAndNoAttendeeIsAdded()
+    {
+        // the owner is only ever ORGANIZER, never ATTENDEE
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'bookings@example.com');
+
+        $user = new FakeUserSession();
+        $res = new ReservationItemView();
+        $res->OwnerId = $user->UserId;
+        $res->OwnerFirstName = 'f';
+        $res->OwnerLastName = 'l';
+        $res->OwnerEmailAddress = 'e@m.com';
+        $res->StartDate = Date::Now();
+        $res->EndDate = Date::Now()->AddHours(1);
+
+        $this->privacyFilter->_CanViewDetails = true;
+        $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter);
+
+        $this->fakeConfig->_ScriptUrl = 'https://example.com/Web';
+        $display = new CalendarExportDisplay();
+        $ics = $display->Render([$reservationView]);
+        $unfolded = str_replace("\r\n ", '', $ics);
+
+        $this->assertMatchesRegularExpression('/ORGANIZER;CN=f l;SENT-BY="mailto:bookings@example\.com":mailto:e@m\.com/', $unfolded);
+        $this->assertStringNotContainsString('ATTENDEE', $ics);
     }
 
     public function testViewHidesDetailsWhenNoAccess()
@@ -134,6 +186,7 @@ public function testViewHidesDetailsWhenNoAccess()
         $this->privacyFilter->_CanViewDetails = false;
         $this->privacyFilter->_CanViewUser = false;
         $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'noreply@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'LB');
 
         $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter);
 
@@ -143,8 +196,10 @@ public function testViewHidesDetailsWhenNoAccess()
         $this->assertEquals($res, $this->privacyFilter->_LastViewDetailsReservation);
         $this->assertEquals($res, $this->privacyFilter->_LastViewUserReservation);
 
+        // hidden owner: ORGANIZER is the default address, without SENT-BY
         $this->assertEquals('Private', $reservationView->Organizer);
         $this->assertEquals('noreply@example.com', $reservationView->OrganizerEmail);
+        $this->assertNull($reservationView->OrganizerSentBy);
         $this->assertEquals('Private', $reservationView->Summary);
         $this->assertEquals('Private', $reservationView->Description);
     }
@@ -200,6 +255,7 @@ public function testAnonymousUserSeesPrivateWhenPublicReservationViewingIsDisabl
         // privacy.view.reservations=false (default) means anonymous users must not see any details
         $this->fakeConfig->SetKey(ConfigKeys::PRIVACY_VIEW_RESERVATIONS, false);
         $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'noreply@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'LB');
         $this->privacyFilter->_CanViewDetails = true;
         $this->privacyFilter->_CanViewUser = true;
 
@@ -207,8 +263,10 @@ public function testAnonymousUserSeesPrivateWhenPublicReservationViewingIsDisabl
 
         $this->assertEquals('Private', $reservationView->Summary);
         $this->assertEquals('Private', $reservationView->Description);
+        // anonymous viewers also lose the owner, as in the hidden-owner case
         $this->assertEquals('Private', $reservationView->Organizer);
         $this->assertEquals('noreply@example.com', $reservationView->OrganizerEmail);
+        $this->assertNull($reservationView->OrganizerSentBy);
     }
 
     public function testViewStoresRawTextInSummaryAndDescription()
@@ -327,16 +385,16 @@ public function testExtraIcalLinesPreservesPropertyParametersAndNestedComponents
         $this->privacyFilter->_CanViewDetails = true;
 
         $reservationView = new iCalendarReservationView($res, $user, $this->privacyFilter, '{title}');
-        // ATTENDEE carries parameters; VALARM is a nested component. Both must round-trip
+        // a parameterised property and a nested VALARM must round-trip
         // through Reader::read() rather than becoming malformed flat text.
-        $reservationView->ExtraIcalLines = "ATTENDEE;CN=JaneDoe;ROLE=REQ-PARTICIPANT:mailto:jane@example.com\r\n"
+        $reservationView->ExtraIcalLines = "CATEGORIES;LANGUAGE=en:Meeting\r\n"
             . "BEGIN:VALARM\r\nACTION:AUDIO\r\nTRIGGER:-PT15M\r\nEND:VALARM";
 
         $this->fakeConfig->_ScriptUrl = 'https://example.com/Web';
         $display = new CalendarExportDisplay();
         $ics = $display->Render([$reservationView]);
 
-        $this->assertStringContainsString('ATTENDEE;CN=JaneDoe;ROLE=REQ-PARTICIPANT:mailto:jane@example.com', $ics);
+        $this->assertStringContainsString('CATEGORIES;LANGUAGE=en:Meeting', $ics);
         $this->assertStringContainsString('BEGIN:VALARM', $ics);
         $this->assertStringContainsString('ACTION:AUDIO', $ics);
     }
@@ -401,4 +459,94 @@ public function testMalformedExtraIcalLinesIsSkippedWithoutBreakingTheExport()
         $this->assertStringContainsString('good-ref', $ics);
         $this->assertStringContainsString('bad-ref', $ics);
     }
+
+    /**
+     * Both privacy settings through the real PrivacyFilter, for every method.
+     *
+     * @return array<string, array{bool, bool, string, IcsMethod}>
+     */
+    public static function privacyMatrix(): array
+    {
+        $rows = [];
+        foreach (IcsMethod::cases() as $method) {
+            foreach ([[false, false], [true, false], [false, true], [true, true]] as [$hideUser, $hideDetails]) {
+                $rows[sprintf('stranger user=%d details=%d %s', $hideUser, $hideDetails, $method->value)] = [$hideUser, $hideDetails, 'stranger', $method];
+            }
+            foreach (['owner', 'admin'] as $viewer) {
+                $rows[sprintf('%s user=1 details=1 %s', $viewer, $method->value)] = [true, true, $viewer, $method];
+            }
+        }
+
+        return $rows;
+    }
+
+    #[\PHPUnit\Framework\Attributes\DataProvider('privacyMatrix')]
+    public function testPrivacySettingsApplyToEveryMethod(bool $hideUser, bool $hideDetails, string $viewer, IcsMethod $method)
+    {
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'bookings@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'Example Bookings');
+        $this->fakeConfig->SetKey(ConfigKeys::PRIVACY_HIDE_USER_DETAILS, $hideUser ? 'true' : 'false');
+        $this->fakeConfig->SetKey(ConfigKeys::PRIVACY_HIDE_RESERVATION_DETAILS, $hideDetails ? 'true' : 'false');
+        $this->fakeConfig->_ScriptUrl = 'https://example.com/Web';
+        // only the viewer's resource permission lookup returns a row
+        ServiceLocator::SetDatabase(new class () extends FakeDatabase {
+            public function Query(ISqlCommand $command)
+            {
+                parent::Query($command);
+
+                return new FakeReader($command instanceof GetUserPermissionsCommand ? [[ColumnNames::RESOURCE_ID => 1]] : []);
+            }
+        });
+
+        $ownerId = 1;
+        $session = match ($viewer) {
+            'owner' => new FakeUserSession(false, 'UTC', $ownerId),
+            'admin' => new FakeUserSession(true, 'UTC', 3),
+            default => new FakeUserSession(false, 'UTC', 2),
+        };
+
+        $res = new ReservationItemView();
+        $res->ResourceId = 1;
+        $res->UserId = $ownerId;
+        $res->UserLevelId = ReservationUserLevel::OWNER;
+        $res->OwnerId = $ownerId;
+        $res->OwnerFirstName = 'f';
+        $res->OwnerLastName = 'l';
+        $res->OwnerEmailAddress = 'e@m.com';
+        $res->Title = 'Secret Title';
+        $res->Description = 'Secret Description';
+        $res->StartDate = Date::Now();
+        $res->EndDate = Date::Now()->AddHours(1);
+
+        $view = new iCalendarReservationView($res, $session, new PrivacyFilter($this->createMock(IReservationAuthorization::class)), '{title}');
+        $ics = str_replace("\r\n ", '', (new CalendarExportDisplay())->Render([$view], null, $method));
+
+        $seesUser = !$hideUser || $viewer !== 'stranger';
+        $seesDetails = !$hideDetails || $viewer !== 'stranger';
+
+        $this->assertStringContainsString('METHOD:' . $method->value, $ics);
+        $this->assertStringContainsString($method === IcsMethod::CANCEL ? 'STATUS:CANCELLED' : 'STATUS:CONFIRMED', $ics);
+        $invitation = $method !== IcsMethod::PUBLISH;
+        if ($seesUser && $invitation) {
+            // the site is the organizer and the owner the only attendee
+            $this->assertStringContainsString('ORGANIZER;CN=Example Bookings:mailto:bookings@example.com', $ics);
+            $this->assertSame(1, substr_count($ics, 'ATTENDEE;'));
+            $this->assertStringContainsString('ATTENDEE;CN=f l;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=FALSE:mailto:e@m.com', $ics);
+        } elseif ($seesUser) {
+            $this->assertStringContainsString('ORGANIZER;CN=f l;SENT-BY="mailto:bookings@example.com":mailto:e@m.com', $ics);
+            $this->assertStringNotContainsString('ATTENDEE', $ics);
+        } else {
+            $this->assertStringNotContainsString('ATTENDEE', $ics);
+            $this->assertStringContainsString('ORGANIZER;CN=Private:mailto:bookings@example.com', $ics);
+            $this->assertStringNotContainsString('e@m.com', $ics);
+        }
+        if ($seesDetails) {
+            $this->assertStringContainsString('SUMMARY:Secret Title', $ics);
+            $this->assertStringContainsString('DESCRIPTION:Secret Description', $ics);
+        } else {
+            $this->assertStringContainsString('SUMMARY:Private', $ics);
+            $this->assertStringContainsString('DESCRIPTION:Private', $ics);
+            $this->assertStringNotContainsString('Secret', $ics);
+        }
+    }
 }
diff --git a/tests/fakes/namespace.php b/tests/fakes/namespace.php
index e19107a94..03d354a73 100644
--- a/tests/fakes/namespace.php
+++ b/tests/fakes/namespace.php
@@ -28,6 +28,7 @@
 require_once(ROOT_DIR . 'tests/fakes/TestDateRange.php');
 require_once(ROOT_DIR . 'tests/fakes/TestReservation.php');
 require_once(ROOT_DIR . 'tests/fakes/TestReservationSeries.php');
+require_once(ROOT_DIR . 'tests/fakes/TestReservationEmailMessage.php');
 require_once(ROOT_DIR . 'tests/fakes/FakeEmailMessage.php');
 require_once(ROOT_DIR . 'tests/fakes/FakePluginManager.php');
 require_once(ROOT_DIR . 'tests/fakes/FakeRegistrationPage.php');
diff --git a/tests/lib/Email/EmailServiceTest.php b/tests/lib/Email/EmailServiceTest.php
index adb651143..643021427 100644
--- a/tests/lib/Email/EmailServiceTest.php
+++ b/tests/lib/Email/EmailServiceTest.php
@@ -67,7 +67,7 @@ public function testAttachmentIsAddedWithItsMimeType()
         $message->AddStringAttachment(
             contents: 'BEGIN:VCALENDAR...',
             fileName: 'reservation.ics',
-            mimeType: 'text/calendar; charset=UTF-8; method=REQUEST'
+            mimeType: 'text/calendar; charset=UTF-8; method=PUBLISH'
         );
 
         $phpMailer->expects($this->once())
@@ -76,7 +76,7 @@ public function testAttachmentIsAddedWithItsMimeType()
                 $this->equalTo('BEGIN:VCALENDAR...'),
                 $this->equalTo('reservation.ics'),
                 $this->anything(),
-                $this->equalTo('text/calendar; charset=UTF-8; method=REQUEST')
+                $this->equalTo('text/calendar; charset=UTF-8; method=PUBLISH')
             );
 
         $service = new EmailService($phpMailer);
diff --git a/tests/lib/Email/Messages/ReservationEmailMessageTest.php b/tests/lib/Email/Messages/ReservationEmailMessageTest.php
index 86ce268df..3b902eb22 100644
--- a/tests/lib/Email/Messages/ReservationEmailMessageTest.php
+++ b/tests/lib/Email/Messages/ReservationEmailMessageTest.php
@@ -2,14 +2,22 @@
 
 declare(strict_types=1);
 
-require_once(ROOT_DIR . 'lib/Email/EmailService.php');
-require_once(ROOT_DIR . 'tests/fakes/TestReservationEmailMessage.php');
+use LibreBooking\Calendar\IcsMethod;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+require_once(ROOT_DIR . 'lib/Email/Messages/ReservationEmailMessage.php');
+foreach (['ReservationCreatedEmail', 'ReservationUpdatedEmail', 'ReservationApprovedEmail', 'ReservationDeletedEmail', 'ReservationShareEmail', 'GuestAddedEmail', 'GuestDeletedEmail', 'InviteeAddedEmail', 'ParticipantAddedEmail'] as $emailClass) {
+    require_once(ROOT_DIR . "lib/Email/Messages/{$emailClass}.php");
+}
 
 class ReservationEmailMessageTest extends TestBase
 {
     public function setUp(): void
     {
         parent::setup();
+
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_ADDRESS, 'bookings@example.com');
+        $this->fakeConfig->SetKey(ConfigKeys::EMAIL_DEFAULT_FROM_NAME, 'Example Bookings');
     }
 
     public function teardown(): void
@@ -17,35 +25,159 @@ public function teardown(): void
         parent::teardown();
     }
 
-    public function testIcsAttachmentMimeTypeReachesPhpMailerThroughEmailService()
+    public function testIcsAttachmentListsOnlyTheOwnerAsAttendeeEvenWhenParticipantsExist()
     {
+        // other participants are invited by separate emails
         $ownerId = 1;
         $owner = new FakeUser($ownerId, 'owner@example.com');
         $owner->ChangeName('Owner', 'Person');
 
+        $participantId = 2;
+        $inviteeId = 3;
+
+        $userRepo = new FakeUserRepository();
+        $userRepo->_UserDtos[$participantId] = new UserDto($participantId, 'Part', 'One', 'part1@example.com');
+        $userRepo->_UserDtos[$inviteeId] = new UserDto($inviteeId, 'Invite', 'Two', 'invite2@example.com');
+
         $instance = new TestReservation();
+        $instance->WithParticipant($participantId);
+        $instance->WithInvitee($inviteeId);
+        $instance->WithParticipatingGuest('guest1@example.com');
+        $instance->WithInvitedGuest('guest2@example.com');
 
         $series = new TestReservationSeries();
         $series->WithOwnerId($ownerId);
         $series->WithCurrentInstance($instance);
 
-        $message = new TestReservationEmailMessage($owner, $series, null, new FakeAttributeRepository(), new FakeUserRepository());
-        $message->PopulateIcsAttachmentForTest($instance);
+        $attributeRepo = new FakeAttributeRepository();
+
+        $message = new TestReservationEmailMessage($owner, $series, null, $attributeRepo, $userRepo);
+        $message->PopulateIcsAttachmentForTest($instance, []);
 
+        $ics = $message->AttachmentContents();
+        $unfolded = str_replace("\r\n ", '', $ics);
+
+        $this->assertStringContainsString('METHOD:REQUEST', $ics);
         $this->assertEquals('text/calendar; charset=UTF-8; method=REQUEST', $message->AttachmentMimeType());
-        $this->assertEquals('reservation.ics', $message->AttachmentFileName());
-
-        $phpMailer = $this->createMock('PHPMailer\PHPMailer\PHPMailer');
-        $phpMailer->expects($this->once())
-            ->method('addStringAttachment')
-            ->with(
-                $this->stringContains('BEGIN:VCALENDAR'),
-                $this->equalTo('reservation.ics'),
-                $this->anything(),
-                $this->equalTo('text/calendar; charset=UTF-8; method=REQUEST')
-            );
-
-        $service = new EmailService($phpMailer);
-        $service->Send($message);
+        // the site's default address is the organizer and the owner the only attendee
+        $this->assertStringContainsString('ORGANIZER;CN=Example Bookings:mailto:bookings@example.com', $unfolded);
+        $this->assertSame(1, substr_count($unfolded, 'ATTENDEE'));
+        $this->assertStringContainsString('ATTENDEE;CN=Owner Person;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=FALSE:mailto:owner@example.com', $unfolded);
+    }
+
+    /**
+     * @return array<string, array{class-string, string, IcsMethod}>
+     */
+    public static function emailTypes(): array
+    {
+        $rows = [];
+        $types = [
+            ['ReservationCreatedEmail', 'owner', IcsMethod::REQUEST],
+            ['ReservationUpdatedEmail', 'owner', IcsMethod::REQUEST],
+            ['ReservationApprovedEmail', 'owner', IcsMethod::REQUEST],
+            ['ReservationDeletedEmail', 'owner', IcsMethod::CANCEL],
+            ['ReservationShareEmail', 'address', IcsMethod::REQUEST],
+            ['GuestAddedEmail', 'address', IcsMethod::REQUEST],
+            ['GuestUpdatedEmail', 'address', IcsMethod::REQUEST],
+            ['GuestDeletedEmail', 'address', IcsMethod::CANCEL],
+            ['InviteeAddedEmail', 'user', IcsMethod::REQUEST],
+            ['InviteeUpdatedEmail', 'user', IcsMethod::REQUEST],
+            ['ParticipantAddedEmail', 'user', IcsMethod::REQUEST],
+            ['ParticipantUpdatedEmail', 'user', IcsMethod::REQUEST],
+            ['InviteeRemovedEmail', 'user', IcsMethod::CANCEL],
+        ];
+        foreach ($types as [$class, $recipient, $method]) {
+            $rows[$class] = [$class, $recipient, $method];
+        }
+
+        return $rows;
+    }
+
+    #[DataProvider('emailTypes')]
+    public function testEveryEmailTypeAttachesTheRightMethodWithTheRecipientAsAttendee(string $class, string $recipient, IcsMethod $method)
+    {
+        $owner = new FakeUser(1, 'owner@example.com');
+        $owner->ChangeName('Owner', 'Person');
+
+        $participantId = 2;
+        $userRepo = new FakeUserRepository();
+        $userRepo->_UserDtos[$participantId] = new UserDto($participantId, 'Part', 'One', 'part1@example.com');
+
+        $instance = new TestReservation();
+        $instance->WithParticipant($participantId);
+        $instance->WithInvitedGuest('guest@example.com');
+
+        $series = new TestReservationSeries();
+        $series->WithOwnerId(1);
+        $series->WithCurrentInstance($instance);
+
+        $attributeRepo = new FakeAttributeRepository();
+        $message = match ($recipient) {
+            'owner' => new $class($owner, $series, null, $attributeRepo, $userRepo),
+            'address' => new $class($owner, 'someone@example.com', $series, $attributeRepo, $userRepo),
+            'user' => new $class($owner, new FakeUser(5, 'invitee@example.com'), $series, $attributeRepo, $userRepo),
+        };
+        (fn () => $this->PopulateIcsAttachment($instance, []))->call($message);
+
+        $ics = $message->AttachmentContents();
+
+        $this->assertStringContainsString('METHOD:' . $method->value, $ics);
+        $this->assertEquals('text/calendar; charset=UTF-8; method=' . $method->value, $message->AttachmentMimeType());
+        $this->assertSame(1, substr_count($ics, 'ATTENDEE;'));
+        // the attendee is whoever receives the email
+        $attendee = ['owner' => 'owner@example.com', 'address' => 'someone@example.com', 'user' => 'invitee@example.com'][$recipient];
+        $this->assertStringContainsString(':mailto:' . $attendee, str_replace("\r\n ", '', $ics));
+        if ($method === IcsMethod::CANCEL) {
+            $this->assertStringContainsString('STATUS:CANCELLED', $ics);
+        } else {
+            $this->assertStringNotContainsString('STATUS:CANCELLED', $ics);
+        }
+        // a missing SEQUENCE counts as 0 and the DTSTAMP orders the messages
+        $this->assertStringNotContainsString('SEQUENCE', $ics);
+    }
+
+    public function testUpdatedEmailHasTheSubjectForTheOwnerNotTheOneForAdmins()
+    {
+        $owner = new FakeUser(1, 'owner@example.com');
+        $series = new TestReservationSeries();
+        $series->WithOwnerId(1);
+        $series->WithCurrentInstance(new TestReservation());
+
+        $message = new ReservationUpdatedEmail($owner, $series, null, new FakeAttributeRepository(), new FakeUserRepository());
+
+        $resourceName = $series->Resource()->GetName();
+        $this->assertSame(Resources::GetInstance()->GetString('ReservationUpdatedSubjectWithResource', [$resourceName]), $message->Subject());
+        $this->assertNotSame(Resources::GetInstance()->GetString('ReservationUpdatedAdminSubjectWithResource', [$resourceName]), $message->Subject());
+    }
+
+    public function testIcsAttachmentRendersWithoutBookedBySet()
+    {
+        // date placeholders need a timezone on the fallback session, even if the owner has none
+        $this->fakeConfig->SetKey(ConfigKeys::RESERVATION_LABELS_ICS_SUMMARY, '{title} {startdate}');
+        // the owner session needs permission to the resource to reach the formatting
+        $this->db->SetRows([[ColumnNames::RESOURCE_ID => 1]]);
+
+        $ownerId = 1;
+        $owner = new FakeUser($ownerId, 'owner@example.com');
+        $owner->ChangeName('Owner', 'Person');
+        $owner->SetTimezone('');
+
+        $instance = new TestReservation();
+
+        $series = new TestReservationSeries();
+        $series->WithOwnerId($ownerId);
+        $series->WithCurrentInstance($instance);
+        $series->WithBookedBy(null);
+
+        $userRepo = new FakeUserRepository();
+        $attributeRepo = new FakeAttributeRepository();
+
+        $message = new TestReservationEmailMessage($owner, $series, null, $attributeRepo, $userRepo);
+        $message->PopulateIcsAttachmentForTest($instance, []);
+
+        $ics = $message->AttachmentContents();
+        $unfolded = str_replace("\r\n ", '', $ics);
+
+        $this->assertStringContainsString('ORGANIZER;CN=Example Bookings:mailto:bookings@example.com', $unfolded);
     }
 }
diff --git a/tests/src/Calendar/IcsMethodTest.php b/tests/src/Calendar/IcsMethodTest.php
new file mode 100644
index 000000000..afba6cad0
--- /dev/null
+++ b/tests/src/Calendar/IcsMethodTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LibreBooking\Tests\Calendar;
+
+use LibreBooking\Calendar\IcsMethod;
+use PHPUnit\Framework\TestCase;
+
+class IcsMethodTest extends TestCase
+{
+    public function testValuesAreTheRfc5546MethodNames(): void
+    {
+        $this->assertSame('PUBLISH', IcsMethod::PUBLISH->value);
+        $this->assertSame('REQUEST', IcsMethod::REQUEST->value);
+        $this->assertSame('CANCEL', IcsMethod::CANCEL->value);
+    }
+
+    public function testOnlyTheMethodsOfReservationsAreSupported(): void
+    {
+        $this->assertCount(3, IcsMethod::cases());
+        $this->assertNull(IcsMethod::tryFrom('REPLY'));
+    }
+}