java - Send meeting invitation mail over Google app engine

Question

i want to send iCalendar meeting invitations. I am using Google App engine, Java. I managed to send a mail with an iCalendar file as an attachment, but programs like Outlook do not automatically recognize it as a meeting invitation.

I figure, i have to set the content-type of the attachment to: "text/calendar; method=REQUEST", but it seems to me, GAE is not accepting this?

Update: I was wrong above. I actually found, that i have to send the mail with the iCalendar part directly in the content, not as an attachment! So my problem is, GAE seems not to accept setting the content-type of the message itself.

Has anyone succesfully send a meeting invitation iCalendar element through mail using GAE?

Update:

I understand, i have to be more specific. In fact, i want to send iMip messages. iMip messages are not multipart, their content-type is "text/calendar". And in the case of sending a meeting invitation, it would be "text/calendar;method=REQUEST". So i tried this:

Message msg = new MimeMessage(session);
msg.setContent(iCalendarAsString, "text/calendar;method=REQUEST");

Then i send the message with Transport.send(..);

In the logs in the development server of GAE i then see, that the content type is "text/plain". that's why i said, i think, GAE is not accepting setting a different content type.

Or am i wrong?

Update 2

OK, here's the complete code:

Properties props = new Properties();
Session session = Session.getDefaultInstance(props, null);


try {
    Message msg = new MimeMessage(session);

    msg.setFrom(new InternetAddress("ical@someapp.appspotmail.com", "SomeApp"));
    msg.addRecipient(Message.RecipientType.TO,
            new InternetAddress("me@mydomain.de", "Sven Busse"));
    msg.setSubject("meeting invitation!");
    msg.setContent(iCalendarAsString, "text/calendar;method=REQUEST");

    Transport.send(msg);

} catch (AddressException e) {
    log.warning(e.toString());
    e.printStackTrace();
} catch (MessagingException e) {
    log.warning(e.toString());
    e.printStackTrace();
} catch (UnsupportedEncodingException e) {
    log.warning(e.toString());
    e.printStackTrace();
}

So, i set the content-type to "text/calendar;method=REQUEST". And once i send, this is the logs:

14.09.2011 09:52:59 com.google.appengine.api.mail.dev.LocalMailService log
INFO: MailService.send
INFO:   From: SomeApp <ical@someapp.appspotmail.com>
INFO:   To: Sven Busse <me@mydomain.de>
INFO:   Reply-to: SomeApp <ical@someapp.appspotmail.com>
INFO:   Subject: meeting invitation!
INFO:   Body:
INFO:     Content-type: text/plain
INFO:     Data length: 458

So, the logs don't look pretty, but you can see, the content-type has changed to "text/plain".

Update 3:

Delivered-To: me@mydomain.de
Received: by 10.68.59.7 with SMTP id v7cs112540pbq;
        Thu, 15 Sep 2011 07:45:55 -0700 (PDT)
Received: by 10.52.95.44 with SMTP id dh12mr1121151vdb.20.1316097954738;
        Thu, 15 Sep 2011 07:45:54 -0700 (PDT)
Return-Path: <3oQ9yTgoJCgIdqqmngvqpciockn.eqouxgp.dwuugiqqingockn.eqo@2uix4h7xygsz66weerlq.apphosting.bounces.google.com>
Received: from mail-vw0-f69.google.com (mail-vw0-f69.google.com [209.85.212.69])
        by mx.google.com with ESMTPS id o9si1579035vcv.136.2011.09.15.07.45.53
        (version=TLSv1/SSLv3 cipher=OTHER);
        Thu, 15 Sep 2011 07:45:53 -0700 (PDT)
Received-SPF: pass (google.com: domain of 3oQ9yTgoJCgIdqqmngvqpciockn.eqouxgp.dwuugiqqingockn.eqo@2uix4h7xygsz66weerlq.apphosting.bounces.google.com designates 209.85.212.69 as permitted sender) client-ip=209.85.212.69;
Authentication-Results: mx.google.com; spf=pass (google.com: domain of 3oQ9yTgoJCgIdqqmngvqpciockn.eqouxgp.dwuugiqqingockn.eqo@2uix4h7xygsz66weerlq.apphosting.bounces.google.com designates 209.85.212.69 as permitted sender) smtp.mail=3oQ9yTgoJCgIdqqmngvqpciockn.eqouxgp.dwuugiqqingockn.eqo@2uix4h7xygsz66weerlq.apphosting.bounces.google.com
Received: by vws20 with SMTP id 20so3831617vws.4
        for <me@mydomain.de>; Thu, 15 Sep 2011 07:45:53 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.236.187.1 with SMTP id x1mr5481998yhm.8.1316097953249; Thu, 15
 Sep 2011 07:45:53 -0700 (PDT)
Reply-To: SomeApp <ical@someapp.appspotmail.com>
X-Google-Appengine-App-Id: someapp
Message-ID: <20cf305e2551fe38a104acfbee28@google.com>
Date: Thu, 15 Sep 2011 14:45:53 +0000
Subject: meeting invitation!
From: SomeApp <ical@someapp.appspotmail.com>
To: Sven Busse <me@mydomain.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed; delsp=yes

BEGIN:VCALENDAR
PRODID:-//Ben Fortuna//iCal4j 1.0//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:REQUEST
BEGIN:VEVENT
DTSTAMP:20110915T144552Z
UID:20110915T144552Z-1@someapp.appspotmail.com
SUMMARY:tolles projekt, macht viel spass.
DTSTART;VALUE=DATE:20110919
DTEND;VALUE=DATE:20110926
DESCRIPTION:tolles projekt, macht viel spass.
ATTENDEE;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:me@mydomain.de
ORGANIZER:mailto:ical@someapp.appspotmail.com
END:VEVENT
END:VCALENDAR

Answer 1

Waitting for answers