diff --git a/apps/dav/appinfo/v1/caldav.php b/apps/dav/appinfo/v1/caldav.php
index a103f82a42..53f167bea3 100644
--- a/apps/dav/appinfo/v1/caldav.php
+++ b/apps/dav/appinfo/v1/caldav.php
@@ -87,9 +87,8 @@ $server->addPlugin(new \Sabre\CalDAV\ICSExportPlugin());
 $server->addPlugin(new \OCA\DAV\CalDAV\Schedule\Plugin());
 
 if ($sendInvitations) {
-	$server->addPlugin(new \OCA\DAV\CalDAV\Schedule\IMipPlugin( \OC::$server->getMailer(), \OC::$server->getLogger(), new \OC\AppFramework\Utility\TimeFactory()));
+	$server->addPlugin(\OC::$server->query(\OCA\DAV\CalDAV\Schedule\IMipPlugin::class));
 }
-
 $server->addPlugin(new ExceptionLoggerPlugin('caldav', \OC::$server->getLogger()));
 
 // And off we go!
diff --git a/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php b/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
index 8e1d7e2563..889b085133 100644
--- a/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
+++ b/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
@@ -24,14 +24,22 @@
 namespace OCA\DAV\CalDAV\Schedule;
 
 use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
+use OCP\IL10N;
 use OCP\ILogger;
+use OCP\IURLGenerator;
+use OCP\L10N\IFactory as L10NFactory;
+use OCP\Mail\IEMailTemplate;
 use OCP\Mail\IMailer;
-use Sabre\VObject\Component\VCalendar;
-use Sabre\VObject\DateTimeParser;
-use Sabre\VObject\ITip;
 use Sabre\CalDAV\Schedule\IMipPlugin as SabreIMipPlugin;
+use Sabre\DAV\Xml\Element\Prop;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\ITip\Message;
+use Sabre\VObject\Parameter;
+use Sabre\VObject\Property;
 use Sabre\VObject\Recur\EventIterator;
-
 /**
  * iMIP handler.
  *
@@ -48,6 +56,12 @@ use Sabre\VObject\Recur\EventIterator;
  */
 class IMipPlugin extends SabreIMipPlugin {
 
+	/** @var string */
+	private $userId;
+
+	/** @var IConfig */
+	private $config;
+
 	/** @var IMailer */
 	private $mailer;
 
@@ -57,29 +71,45 @@ class IMipPlugin extends SabreIMipPlugin {
 	/** @var ITimeFactory */
 	private $timeFactory;
 
+	/** @var L10NFactory */
+	private $l10nFactory;
+
+	/** @var IURLGenerator */
+	private $urlGenerator;
+
 	const MAX_DATE = '2038-01-01';
 
+	const METHOD_REQUEST = 'request';
+	const METHOD_REPLY = 'reply';
+	const METHOD_CANCEL = 'cancel';
+
 	/**
-	 * Creates the email handler.
-	 *
+	 * @param IConfig $config
 	 * @param IMailer $mailer
 	 * @param ILogger $logger
 	 * @param ITimeFactory $timeFactory
+	 * @param L10NFactory $l10nFactory
+	 * @param IUrlGenerator $urlGenerator
+	 * @param string $userId
 	 */
-	function __construct(IMailer $mailer, ILogger $logger, ITimeFactory $timeFactory) {
+	public function __construct(IConfig $config, IMailer $mailer, ILogger $logger, ITimeFactory $timeFactory, L10NFactory $l10nFactory, IURLGenerator $urlGenerator, $userId) {
 		parent::__construct('');
+		$this->userId = $userId;
+		$this->config = $config;
 		$this->mailer = $mailer;
 		$this->logger = $logger;
 		$this->timeFactory = $timeFactory;
+		$this->l10nFactory = $l10nFactory;
+		$this->urlGenerator = $urlGenerator;
 	}
 
 	/**
 	 * Event handler for the 'schedule' event.
 	 *
-	 * @param ITip\Message $iTipMessage
+	 * @param Message $iTipMessage
 	 * @return void
 	 */
-	function schedule(ITip\Message $iTipMessage) {
+	public function schedule(Message $iTipMessage) {
 
 		// Not sending any emails if the system considers the update
 		// insignificant.
@@ -105,40 +135,100 @@ class IMipPlugin extends SabreIMipPlugin {
 			return;
 		}
 
+		// Strip off mailto:
 		$sender = substr($iTipMessage->sender, 7);
 		$recipient = substr($iTipMessage->recipient, 7);
 
-		$senderName = ($iTipMessage->senderName) ? $iTipMessage->senderName : null;
-		$recipientName = ($iTipMessage->recipientName) ? $iTipMessage->recipientName : null;
+		$senderName = $iTipMessage->senderName ?: null;
+		$recipientName = $iTipMessage->recipientName ?: null;
 
-		$subject = 'SabreDAV iTIP message';
-		switch (strtoupper($iTipMessage->method)) {
-			case 'REPLY' :
-				$subject = 'Re: ' . $summary;
+		/** @var VEvent $vevent */
+		$vevent = $iTipMessage->message->VEVENT;
+
+		$attendee = $this->getCurrentAttendee($iTipMessage);
+		$defaultLang = $this->config->getUserValue($this->userId, 'core', 'lang', $this->l10nFactory->findLanguage());
+		$lang = $this->getAttendeeLangOrDefault($defaultLang, $attendee);
+		$l10n = $this->l10nFactory->get('dav', $lang);
+
+		$meetingAttendeeName = $recipientName ?: $recipient;
+		$meetingInviteeName = $senderName ?: $sender;
+
+		$meetingTitle = $vevent->SUMMARY;
+		$meetingDescription = $vevent->DESCRIPTION;
+
+		$start = $vevent->DTSTART;
+		if (isset($vevent->DTEND)) {
+			$end = $vevent->DTEND;
+		} elseif (isset($vevent->DURATION)) {
+			$isFloating = $vevent->DTSTART->isFloating();
+			$end = clone $vevent->DTSTART;
+			$endDateTime = $end->getDateTime();
+			$endDateTime = $endDateTime->add(DateTimeParser::parse($vevent->DURATION->getValue()));
+			$end->setDateTime($endDateTime, $isFloating);
+		} elseif (!$vevent->DTSTART->hasTime()) {
+			$isFloating = $vevent->DTSTART->isFloating();
+			$end = clone $vevent->DTSTART;
+			$endDateTime = $end->getDateTime();
+			$endDateTime = $endDateTime->modify('+1 day');
+			$end->setDateTime($endDateTime, $isFloating);
+		} else {
+			$end = clone $vevent->DTSTART;
+		}
+
+		$meetingWhen = $this->generateWhenString($l10n, $start, $end);
+
+		$meetingUrl = $vevent->URL;
+		$meetingLocation = $vevent->LOCATION;
+
+		$defaultVal = '--';
+
+		$method = self::METHOD_REQUEST;
+		switch (strtolower($iTipMessage->method)) {
+			case self::METHOD_REPLY:
+				$method = self::METHOD_REPLY;
 				break;
-			case 'REQUEST' :
-				$subject = $summary;
-				break;
-			case 'CANCEL' :
-				$subject = 'Cancelled: ' . $summary;
+			case self::METHOD_CANCEL:
+				$method = self::METHOD_CANCEL;
 				break;
 		}
 
-		$contentType = 'text/calendar; charset=UTF-8; method=' . $iTipMessage->method;
+		$data = array(
+			'attendee_name' => (string)$meetingAttendeeName ?: $defaultVal,
+			'invitee_name' => (string)$meetingInviteeName ?: $defaultVal,
+			'meeting_title' => (string)$meetingTitle ?: $defaultVal,
+			'meeting_description' => (string)$meetingDescription ?: $defaultVal,
+			'meeting_url' => (string)$meetingUrl ?: $defaultVal,
+		);
 
-		$message = $this->mailer->createMessage();
+		$message = $this->mailer->createMessage()
+			->setReplyTo([$sender => $senderName])
+			->setTo([$recipient => $recipientName]);
+
+		$template = $this->mailer->createEMailTemplate('dav.calendarInvite.' . $method, $data);
+		$template->addHeader();
+
+		$this->addSubjectAndHeading($template, $l10n, $method, $summary,
+			$meetingAttendeeName, $meetingInviteeName);
+		$this->addBulletList($template, $l10n, $meetingWhen, $meetingLocation,
+			$meetingDescription, $meetingUrl);
+
+		$template->addFooter();
+		$message->useTemplate($template);
+
+		$attachment = $this->mailer->createAttachment(
+			$iTipMessage->message->serialize(),
+			'event.ics',// TODO(leon): Make file name unique, e.g. add event id
+			'text/calendar; method=' . $iTipMessage->method
+		);
+		$message->attach($attachment);
 
-		$message->setReplyTo([$sender => $senderName])
-			->setTo([$recipient => $recipientName])
-			->setSubject($subject)
-			->setBody($iTipMessage->message->serialize(), $contentType);
 		try {
 			$failed = $this->mailer->send($message);
+			$iTipMessage->scheduleStatus = '1.1; Scheduling message is sent via iMip';
 			if ($failed) {
 				$this->logger->error('Unable to deliver message to {failed}', ['app' => 'dav', 'failed' =>  implode(', ', $failed)]);
 				$iTipMessage->scheduleStatus = '5.0; EMail delivery failed';
 			}
-			$iTipMessage->scheduleStatus = '1.1; Scheduling message is sent via iMip';
 		} catch(\Exception $ex) {
 			$this->logger->logException($ex, ['app' => 'dav']);
 			$iTipMessage->scheduleStatus = '5.0; EMail delivery failed';
@@ -151,6 +241,7 @@ class IMipPlugin extends SabreIMipPlugin {
 	 * @return bool
 	 */
 	private function isEventInThePast(VCalendar $vObject) {
+		/** @var VEvent $component */
 		$component = $vObject->VEVENT;
 
 		$firstOccurrence = $component->DTSTART->getDateTime()->getTimeStamp();
@@ -159,15 +250,17 @@ class IMipPlugin extends SabreIMipPlugin {
 			if (isset($component->DTEND)) {
 				$lastOccurrence = $component->DTEND->getDateTime()->getTimeStamp();
 			} elseif (isset($component->DURATION)) {
+				/** @var \DateTime $endDate */
 				$endDate = clone $component->DTSTART->getDateTime();
 				// $component->DTEND->getDateTime() returns DateTimeImmutable
 				$endDate = $endDate->add(DateTimeParser::parse($component->DURATION->getValue()));
-				$lastOccurrence = $endDate->getTimeStamp();
+				$lastOccurrence = $endDate->getTimestamp();
 			} elseif (!$component->DTSTART->hasTime()) {
+				/** @var \DateTime $endDate */
 				$endDate = clone $component->DTSTART->getDateTime();
 				// $component->DTSTART->getDateTime() returns DateTimeImmutable
 				$endDate = $endDate->modify('+1 day');
-				$lastOccurrence = $endDate->getTimeStamp();
+				$lastOccurrence = $endDate->getTimestamp();
 			} else {
 				$lastOccurrence = $firstOccurrence;
 			}
@@ -190,4 +283,176 @@ class IMipPlugin extends SabreIMipPlugin {
 		$currentTime = $this->timeFactory->getTime();
 		return $lastOccurrence < $currentTime;
 	}
+
+
+	/**
+	 * @param Message $iTipMessage
+	 * @return null|Property
+	 */
+	private function getCurrentAttendee(Message $iTipMessage) {
+		/** @var VEvent $vevent */
+		$vevent = $iTipMessage->message->VEVENT;
+		$attendees = $vevent->select('ATTENDEE');
+		foreach ($attendees as $attendee) {
+			/** @var Property $attendee */
+			if (strcasecmp($attendee->getValue(), $iTipMessage->recipient) === 0) {
+				return $attendee;
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * @param string $default
+	 * @param Property|null $attendee
+	 * @return string
+	 */
+	private function getAttendeeLangOrDefault($default, Property $attendee = null) {
+		if ($attendee !== null) {
+			$lang = $attendee->offsetGet('LANGUAGE');
+			if ($lang instanceof Parameter) {
+				return $lang->getValue();
+			}
+		}
+		return $default;
+	}
+
+	/**
+	 * @param IL10N $l10n
+	 * @param Property $dtstart
+	 * @param Property $dtend
+	 */
+	private function generateWhenString(IL10N $l10n, Property $dtstart, Property $dtend) {
+		$isAllDay = $dtstart instanceof Property\ICalendar\Date;
+
+		/** @var Property\ICalendar\Date | Property\ICalendar\DateTime $dtstart */
+		/** @var Property\ICalendar\Date | Property\ICalendar\DateTime $dtend */
+		/** @var \DateTimeImmutable $dtstartDt */
+		$dtstartDt = $dtstart->getDateTime();
+		/** @var \DateTimeImmutable $dtendDt */
+		$dtendDt = $dtend->getDateTime();
+
+		$diff = $dtstartDt->diff($dtendDt);
+
+		$dtstartDt = new \DateTime($dtstartDt->format(\DateTime::ATOM));
+		$dtendDt = new \DateTime($dtendDt->format(\DateTime::ATOM));
+
+		if ($isAllDay) {
+			// One day event
+			if ($diff->days === 1) {
+				return $l10n->l('date', $dtstartDt, ['width' => 'medium']);
+			}
+
+			//event that spans over multiple days
+			$localeStart = $l10n->l('date', $dtstartDt, ['width' => 'medium']);
+			$localeEnd = $l10n->l('date', $dtendDt, ['width' => 'medium']);
+
+			return $localeStart . ' - ' . $localeEnd;
+		}
+
+		/** @var Property\ICalendar\DateTime $dtstart */
+		/** @var Property\ICalendar\DateTime $dtend */
+		$isFloating = $dtstart->isFloating();
+		$startTimezone = $endTimezone = null;
+		if (!$isFloating) {
+			$prop = $dtstart->offsetGet('TZID');
+			if ($prop instanceof Parameter) {
+				$startTimezone = $prop->getValue();
+			}
+
+			$prop = $dtend->offsetGet('TZID');
+			if ($prop instanceof Parameter) {
+				$endTimezone = $prop->getValue();
+			}
+		}
+
+		$localeStart = $l10n->l('datetime', $dtstartDt, ['width' => 'medium']);
+
+		// always show full date with timezone if timezones are different
+		if ($startTimezone !== $endTimezone) {
+			$localeEnd = $l10n->l('datetime', $dtendDt, ['width' => 'medium']);
+
+			return $localeStart . ' (' . $startTimezone . ') - ' .
+				$localeEnd . ' (' . $endTimezone . ')';
+		}
+
+		// show only end time if date is the same
+		if ($this->isDayEqual($dtstartDt, $dtendDt)) {
+			$localeEnd = $l10n->l('time', $dtendDt, ['width' => 'medium']);
+		} else {
+			$localeEnd = $l10n->l('datetime', $dtendDt, ['width' => 'medium']);
+		}
+
+		return  $localeStart . ' - ' . $localeEnd . ' (' . $startTimezone . ')';
+	}
+
+	/**
+	 * @param \DateTime $dtStart
+	 * @param \DateTime $dtEnd
+	 * @return bool
+	 */
+	private function isDayEqual(\DateTime $dtStart, \DateTime $dtEnd) {
+		return $dtStart->format('Y-m-d') === $dtEnd->format('Y-m-d');
+	}
+
+	/**
+	 * @param IEMailTemplate $template
+	 * @param IL10N $l10n
+	 * @param string $method
+	 * @param string $summary
+	 * @param string $attendeeName
+	 * @param string $inviteeName
+	 */
+	private function addSubjectAndHeading(IEMailTemplate $template, IL10N $l10n,
+										  $method, $summary, $attendeeName, $inviteeName) {
+		if ($method === self::METHOD_CANCEL) {
+			$template->setSubject('Cancelled: ' . $summary);
+			$template->addHeading($l10n->t('Invitation canceled'), $l10n->t('Hello %s,', [$attendeeName]));
+			$template->addBodyText($l10n->t('The meeting »%s« with %s was canceled.', [$summary, $inviteeName]));
+		} else if ($method === self::METHOD_REPLY) {
+			$template->setSubject('Re: ' . $summary);
+			$template->addHeading($l10n->t('Invitation updated'), $l10n->t('Hello %s,', [$attendeeName]));
+			$template->addBodyText($l10n->t('The meeting »%s« with %s was updated.', [$summary, $inviteeName]));
+		} else {
+			$template->setSubject('Invitation: ' . $summary);
+			$template->addHeading($l10n->t('%s invited you to »%s«', [$inviteeName, $summary]), $l10n->t('Hello %s,', [$attendeeName]));
+		}
+
+	}
+
+	/**
+	 * @param IEMailTemplate $template
+	 * @param IL10N $l10n
+	 * @param string $time
+	 * @param string $location
+	 * @param string $description
+	 * @param string $url
+	 */
+	private function addBulletList(IEMailTemplate $template, IL10N $l10n, $time, $location, $description, $url) {
+		$template->addBodyListItem($time, $l10n->t('When:'),
+			$this->getAbsoluteImagePath('filetypes/text-calendar.svg'));
+
+		if ($location) {
+			$template->addBodyListItem($location, $l10n->t('Where:'),
+				$this->getAbsoluteImagePath('filetypes/location.svg'));
+		}
+		if ($description) {
+			$template->addBodyListItem((string)$description, $l10n->t('Description:'),
+				$this->getAbsoluteImagePath('filetypes/text.svg'));
+		}
+		if ($url) {
+			$template->addBodyListItem((string)$url, $l10n->t('Link:'),
+				$this->getAbsoluteImagePath('filetypes/link.svg'));
+		}
+	}
+
+	/**
+	 * @param string $path
+	 * @return string
+	 */
+	private function getAbsoluteImagePath($path) {
+		return $this->urlGenerator->getAbsoluteURL(
+			$this->urlGenerator->imagePath('core', $path)
+		);
+	}
 }
diff --git a/apps/dav/lib/Server.php b/apps/dav/lib/Server.php
index 719e497475..dfe55959a9 100644
--- a/apps/dav/lib/Server.php
+++ b/apps/dav/lib/Server.php
@@ -77,6 +77,7 @@ class Server {
 		$dispatcher = \OC::$server->getEventDispatcher();
 		$timezone = new TimeFactory();
 		$sendInvitations = \OC::$server->getConfig()->getAppValue('dav', 'sendInvitations', 'yes') === 'yes';
+		$l10nFactory = \OC::$server->getL10NFactory();
 
 		$root = new RootCollection();
 		$this->server = new \OCA\DAV\Connector\Sabre\Server(new CachingTree($root));
@@ -139,7 +140,7 @@ class Server {
 		$this->server->addPlugin(new \Sabre\CalDAV\ICSExportPlugin());
 		$this->server->addPlugin(new \OCA\DAV\CalDAV\Schedule\Plugin());
 		if ($sendInvitations) {
-			$this->server->addPlugin(new IMipPlugin($mailer, $logger, $timezone));
+			$this->server->addPlugin(\OC::$server->query(\OCA\DAV\CalDAV\Schedule\IMipPlugin::class));
 		}
 		$this->server->addPlugin(new \Sabre\CalDAV\Subscriptions\Plugin());
 		$this->server->addPlugin(new \Sabre\CalDAV\Notifications\Plugin());
diff --git a/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php b/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
index 894617781b..664e33dfd0 100644
--- a/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
+++ b/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
@@ -28,7 +28,15 @@ namespace OCA\DAV\Tests\unit\CalDAV\Schedule;
 use OC\Mail\Mailer;
 use OCA\DAV\CalDAV\Schedule\IMipPlugin;
 use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
+use OCP\IL10N;
 use OCP\ILogger;
+use OCP\IURLGenerator;
+use OCP\L10N\IFactory;
+use OCP\Mail\IAttachment;
+use OCP\Mail\IEMailTemplate;
+use OCP\Mail\IMailer;
+use OCP\Mail\IMessage;
 use Sabre\VObject\Component\VCalendar;
 use Sabre\VObject\ITip\Message;
 use Test\TestCase;
@@ -36,17 +44,31 @@ use Test\TestCase;
 class IMipPluginTest extends TestCase {
 
 	public function testDelivery() {
-		$mailMessage = new \OC\Mail\Message(new \Swift_Message());
+		$mailMessage = $this->createMock(IMessage::class);
+		$mailMessage->method('setReplyTo')->willReturn($mailMessage);
+		$mailMessage->method('setTo')->willReturn($mailMessage);
 		/** @var Mailer | \PHPUnit_Framework_MockObject_MockObject $mailer */
-		$mailer = $this->getMockBuilder(Mailer::class)->disableOriginalConstructor()->getMock();
+		$mailer = $this->getMockBuilder(IMailer::class)->disableOriginalConstructor()->getMock();
+		$emailTemplate = $this->createMock(IEMailTemplate::class);
+		$emailAttachment = $this->createMock(IAttachment::class);
+		$mailer->method('createEMailTemplate')->willReturn($emailTemplate);
 		$mailer->method('createMessage')->willReturn($mailMessage);
+		$mailer->method('createAttachment')->willReturn($emailAttachment);
 		$mailer->expects($this->once())->method('send');
 		/** @var ILogger | \PHPUnit_Framework_MockObject_MockObject $logger */
 		$logger = $this->getMockBuilder(ILogger::class)->disableOriginalConstructor()->getMock();
 		$timeFactory = $this->getMockBuilder(ITimeFactory::class)->disableOriginalConstructor()->getMock();
 		$timeFactory->method('getTime')->willReturn(1);
+		/** @var IConfig | \PHPUnit_Framework_MockObject_MockObject $config */
+		$config = $this->createMock(IConfig::class);
+		$l10n = $this->createMock(IL10N::class);
+		/** @var IFactory | \PHPUnit_Framework_MockObject_MockObject $l10nFactory */
+		$l10nFactory = $this->createMock(IFactory::class);
+		$l10nFactory->method('get')->willReturn($l10n);
+		/** @var IURLGenerator | \PHPUnit_Framework_MockObject_MockObject $urlGenerator */
+		$urlGenerator = $this->createMock(IURLGenerator::class);
 
-		$plugin = new IMipPlugin($mailer, $logger, $timeFactory);
+		$plugin = new IMipPlugin($config, $mailer, $logger, $timeFactory, $l10nFactory, $urlGenerator, 'user123');
 		$message = new Message();
 		$message->method = 'REQUEST';
 		$message->message = new VCalendar();
@@ -59,26 +81,46 @@ class IMipPluginTest extends TestCase {
 		$message->sender = 'mailto:gandalf@wiz.ard';
 		$message->recipient = 'mailto:frodo@hobb.it';
 
+		$emailTemplate->expects($this->once())
+			->method('setSubject')
+			->with('Invitation: Fellowship meeting');
+		$mailMessage->expects($this->once())
+			->method('setTo')
+			->with(['frodo@hobb.it' => null]);
+		$mailMessage->expects($this->once())
+			->method('setReplyTo')
+			->with(['gandalf@wiz.ard' => null]);
+
 		$plugin->schedule($message);
 		$this->assertEquals('1.1', $message->getScheduleStatus());
-		$this->assertEquals('Fellowship meeting', $mailMessage->getSubject());
-		$this->assertEquals(['frodo@hobb.it' => null], $mailMessage->getTo());
-		$this->assertEquals(['gandalf@wiz.ard' => null], $mailMessage->getReplyTo());
-		$this->assertEquals('text/calendar; charset=UTF-8; method=REQUEST', $mailMessage->getSwiftMessage()->getContentType());
 	}
 
 	public function testFailedDelivery() {
-		$mailMessage = new \OC\Mail\Message(new \Swift_Message());
+		$mailMessage = $this->createMock(IMessage::class);
+		$mailMessage->method('setReplyTo')->willReturn($mailMessage);
+		$mailMessage->method('setTo')->willReturn($mailMessage);
 		/** @var Mailer | \PHPUnit_Framework_MockObject_MockObject $mailer */
-		$mailer = $this->getMockBuilder(Mailer::class)->disableOriginalConstructor()->getMock();
+		$mailer = $this->getMockBuilder(IMailer::class)->disableOriginalConstructor()->getMock();
+		$emailTemplate = $this->createMock(IEMailTemplate::class);
+		$emailAttachment = $this->createMock(IAttachment::class);
+		$mailer->method('createEMailTemplate')->willReturn($emailTemplate);
 		$mailer->method('createMessage')->willReturn($mailMessage);
+		$mailer->method('createAttachment')->willReturn($emailAttachment);
 		$mailer->method('send')->willThrowException(new \Exception());
 		/** @var ILogger | \PHPUnit_Framework_MockObject_MockObject $logger */
 		$logger = $this->getMockBuilder(ILogger::class)->disableOriginalConstructor()->getMock();
 		$timeFactory = $this->getMockBuilder(ITimeFactory::class)->disableOriginalConstructor()->getMock();
 		$timeFactory->method('getTime')->willReturn(1);
+		/** @var IConfig | \PHPUnit_Framework_MockObject_MockObject $config */
+		$config = $this->createMock(IConfig::class);
+		$l10n = $this->createMock(IL10N::class);
+		/** @var IFactory | \PHPUnit_Framework_MockObject_MockObject $l10nFactory */
+		$l10nFactory = $this->createMock(IFactory::class);
+		$l10nFactory->method('get')->willReturn($l10n);
+		/** @var IURLGenerator | \PHPUnit_Framework_MockObject_MockObject $urlGenerator */
+		$urlGenerator = $this->createMock(IURLGenerator::class);
 
-		$plugin = new IMipPlugin($mailer, $logger, $timeFactory);
+		$plugin = new IMipPlugin($config, $mailer, $logger, $timeFactory, $l10nFactory, $urlGenerator, 'user123');
 		$message = new Message();
 		$message->method = 'REQUEST';
 		$message->message = new VCalendar();
@@ -91,22 +133,34 @@ class IMipPluginTest extends TestCase {
 		$message->sender = 'mailto:gandalf@wiz.ard';
 		$message->recipient = 'mailto:frodo@hobb.it';
 
+		$emailTemplate->expects($this->once())
+			->method('setSubject')
+			->with('Invitation: Fellowship meeting');
+		$mailMessage->expects($this->once())
+			->method('setTo')
+			->with(['frodo@hobb.it' => null]);
+		$mailMessage->expects($this->once())
+			->method('setReplyTo')
+			->with(['gandalf@wiz.ard' => null]);
+
 		$plugin->schedule($message);
 		$this->assertEquals('5.0', $message->getScheduleStatus());
-		$this->assertEquals('Fellowship meeting', $mailMessage->getSubject());
-		$this->assertEquals(['frodo@hobb.it' => null], $mailMessage->getTo());
-		$this->assertEquals(['gandalf@wiz.ard' => null], $mailMessage->getReplyTo());
-		$this->assertEquals('text/calendar; charset=UTF-8; method=REQUEST', $mailMessage->getSwiftMessage()->getContentType());
 	}
 
 	/**
 	 * @dataProvider dataNoMessageSendForPastEvents
 	 */
 	public function testNoMessageSendForPastEvents($veventParams, $expectsMail) {
-		$mailMessage = new \OC\Mail\Message(new \Swift_Message());
+		$mailMessage = $this->createMock(IMessage::class);
+		$mailMessage->method('setReplyTo')->willReturn($mailMessage);
+		$mailMessage->method('setTo')->willReturn($mailMessage);
 		/** @var Mailer | \PHPUnit_Framework_MockObject_MockObject $mailer */
-		$mailer = $this->getMockBuilder(Mailer::class)->disableOriginalConstructor()->getMock();
+		$mailer = $this->getMockBuilder(IMailer::class)->disableOriginalConstructor()->getMock();
+		$emailTemplate = $this->createMock(IEMailTemplate::class);
+		$emailAttachment = $this->createMock(IAttachment::class);
+		$mailer->method('createEMailTemplate')->willReturn($emailTemplate);
 		$mailer->method('createMessage')->willReturn($mailMessage);
+		$mailer->method('createAttachment')->willReturn($emailAttachment);
 		if ($expectsMail) {
 			$mailer->expects($this->once())->method('send');
 		} else {
@@ -116,8 +170,16 @@ class IMipPluginTest extends TestCase {
 		$logger = $this->getMockBuilder(ILogger::class)->disableOriginalConstructor()->getMock();
 		$timeFactory = $this->getMockBuilder(ITimeFactory::class)->disableOriginalConstructor()->getMock();
 		$timeFactory->method('getTime')->willReturn(1496912528);
+		/** @var IConfig | \PHPUnit_Framework_MockObject_MockObject $config */
+		$config = $this->createMock(IConfig::class);
+		$l10n = $this->createMock(IL10N::class);
+		/** @var IFactory | \PHPUnit_Framework_MockObject_MockObject $l10nFactory */
+		$l10nFactory = $this->createMock(IFactory::class);
+		$l10nFactory->method('get')->willReturn($l10n);
+		/** @var IURLGenerator | \PHPUnit_Framework_MockObject_MockObject $urlGenerator */
+		$urlGenerator = $this->createMock(IURLGenerator::class);
 
-		$plugin = new IMipPlugin($mailer, $logger, $timeFactory);
+		$plugin = new IMipPlugin($config, $mailer, $logger, $timeFactory, $l10nFactory, $urlGenerator, 'user123');
 		$message = new Message();
 		$message->method = 'REQUEST';
 		$message->message = new VCalendar();
diff --git a/lib/private/L10N/L10N.php b/lib/private/L10N/L10N.php
index 620c99dd1e..19db04a7cd 100644
--- a/lib/private/L10N/L10N.php
+++ b/lib/private/L10N/L10N.php
@@ -169,6 +169,8 @@ class L10N implements IL10N {
 				return (string) Calendar::formatDatetime($value, $width, $locale);
 			case 'time':
 				return (string) Calendar::formatTime($value, $width, $locale);
+			case 'weekdayName':
+				return (string) Calendar::getWeekdayName($value, $width, $locale);
 			default:
 				return false;
 		}
diff --git a/tests/lib/L10N/L10nTest.php b/tests/lib/L10N/L10nTest.php
index 6d662efee2..703aa9e227 100644
--- a/tests/lib/L10N/L10nTest.php
+++ b/tests/lib/L10N/L10nTest.php
@@ -164,4 +164,9 @@ class L10nTest extends TestCase {
 		$l = \OC::$server->getL10N('lib', 'de');
 		$this->assertEquals('de', $l->getLanguageCode());
 	}
+
+	public function testWeekdayName() {
+		$l = \OC::$server->getL10N('lib', 'de');
+		$this->assertEquals('Mo.', $l->l('weekdayName', new \DateTime('2017-11-6'), ['width' => 'abbreviated']));
+	}
 }