diff --git a/lib/Service/Proposal/ProposalService.php b/lib/Service/Proposal/ProposalService.php
index 11908f5f2f..5fc46449d0 100644
--- a/lib/Service/Proposal/ProposalService.php
+++ b/lib/Service/Proposal/ProposalService.php
@@ -18,6 +18,7 @@
 use OCA\Calendar\Objects\Proposal\ProposalObject;
 use OCA\Calendar\Objects\Proposal\ProposalParticipantCollection;
 use OCA\Calendar\Objects\Proposal\ProposalParticipantObject;
+use OCA\Calendar\Objects\Proposal\ProposalParticipantRealm;
 use OCA\Calendar\Objects\Proposal\ProposalParticipantStatus;
 use OCA\Calendar\Objects\Proposal\ProposalResponseObject;
 use OCA\Calendar\Objects\Proposal\ProposalVoteCollection;
@@ -35,6 +36,7 @@
 use OCP\Mail\Provider\IMessageSend;
 use Psr\Log\LoggerInterface;
 use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VEvent;
 use Symfony\Component\Uid\Uuid;
 
 class ProposalService {
@@ -193,6 +195,9 @@ public function createProposal(IUser $user, ProposalObject $proposal): ProposalO
 		// generate notifications for internal and external participants
 		$this->generateNotifications($user, $proposal, 'C');
 
+		// generate iTip for internal participants
+		$this->generateIMip($user, $proposal, 'C');
+
 		return $proposal;
 	}
 
@@ -257,6 +262,9 @@ public function modifyProposal(IUser $user, ProposalObject $mutatedProposal): Pr
 		// generate notifications for internal and external participants
 		$this->generateNotifications($user, $proposal, 'M');
 
+		// generate iTip for internal participants
+		$this->generateIMip($user, $proposal, 'M');
+
 		return $proposal;
 	}
 
@@ -277,6 +285,9 @@ public function destroyProposal(IUser $user, int $identifier): void {
 
 		// generate notifications for internal and external participants
 		$this->generateNotifications($user, $proposal, 'D');
+
+		// generate iTip for internal participants
+		$this->generateIMip($user, $proposal, 'D');
 	}
 
 	/**
@@ -548,4 +559,70 @@ private function sendEmailNotifications(IUser $user, ProposalObject $proposal, P
 		}
 
 	}
+
+	private function generateIMip(IUser $user, ProposalObject $proposal, string $reason): void {
+		// if the calendar manager does not have a handleIMip method, we cannot generate iTip messages
+		if (!method_exists($this->calendarManager, 'handleIMip')) {
+			return;
+		}
+		// if the proposal has no dates or participants, we cannot generate any iTip messages
+		if ($proposal->getDates()->count() === 0 || $proposal->getParticipants()->count() === 0) {
+			return;
+		}
+		// construct calendar object with events
+		$template = new VCalendar();
+		// TODO: change REQUEST to PUBLISH
+		$template->add('METHOD', $reason !== 'D' ? 'REQUEST' : 'CANCEL');
+		// create a event for each date in the proposal
+		// TODO: should we create a new instance for each date or use a recurrence rule? Like RDATE:19970714T083000Z,19970715T083000Z
+		foreach ($proposal->getDates()->sortByDate() as $proposalDate) {
+			/** @var VEvent $vEvent */
+			$vEvent = $template->add('VEVENT', []);
+			if (isset($baseDate)) {
+				$vEvent->add('RECURRENCE-ID', $baseDate->getDate()->format('Ymd\THis\Z'));
+			} else {
+				$baseDate = $proposalDate;
+			}
+			$vEvent->UID->setValue($proposal->getUuid());
+			$vEvent->add('STATUS', 'TENTATIVE');
+			$vEvent->add('SEQUENCE', 1);
+			$vEvent->add('DTSTART', $proposalDate->getDate());
+			$vEvent->add('DURATION', "PT{$proposal->getDuration()}M");
+			$vEvent->add('SUMMARY', $proposal->getTitle());
+			$vEvent->add('DESCRIPTION', $proposal->getDescription());
+			$vEvent->add('ORGANIZER', 'mailto:' . $user->getEMailAddress(), ['CN' => $user->getDisplayName()]);
+			// add the participant to the event
+			foreach ($proposal->getParticipants() as $participant) {
+				$vEvent->add('ATTENDEE', 'mailto:' . $participant->getAddress(), [
+					'CN' => $participant->getName(),
+					'CUTYPE' => 'INDIVIDUAL',
+					'PARTSTAT' => 'NEEDS-ACTION',
+					'ROLE' => 'REQ-PARTICIPANT'
+				]);
+			}
+		}
+
+		foreach ($proposal->getParticipants()->filterByRealm(ProposalParticipantRealm::Internal) as $participant) {
+			// TODO: this is stupid, we send the internal users email address from the UI then convert it back to a user name
+			// should probably be sent from the UI as a user name, or send and store both the user name and email address
+			// maybe send the address as a special schema "local:{user name}/{email address}", this would allow us to later extend this to federated users
+			// with a different special schema like "federated:{user name}@{server}/{email address}"
+			$participantUsers = $this->userManager->getByEmail($participant->getAddress());
+			if ($participantUsers === []) {
+				continue;
+			}
+			$participantUser = $participantUsers[0];
+			try {
+				$this->calendarManager->handleIMip(
+					$participantUser->getUID(),
+					$template->serialize(),
+					$reason !== 'D' ? ['absent' => 'create'] : []
+				);
+			} catch (Exception $e) {
+				$this->logger->error($e->getMessage(), ['app' => 'calendar', 'exception' => $e]);
+			}
+		}
+
+	}
+
 }