Google Apps Gmail Can’t Interpret Emails Sent by BPOS / Microsoft Online Services – winmail.dat issue

SADA Says | Cloud Computing Blog

By SADA Says | Cloud Computing Blog

As the pace by which organizations are migrating their email to the cloud, all types of anomalies and gotchas are discovered by our engineers – and this is expected. This is all new, after all.

One of the most surprising, however, is the simple fact that email sent by the BPOS / Microsoft Online Services exchange servers is unable to be interpreted by recipients who use Google Apps Gmail. Since its creation, email has had the key benefit of being very standards based – users from any platform X have been able to send emails to users on any platform Y with general ease.

Now, we’re not the first to report this issue – in fact, discussions around the Google Apps Gmail & MS Online issue seemed to have been taking place since December 2008. Also, Google Apps Gmail is not the only destination server which seems to have this problem when receiving email from BPOS (interpretation issues from Groupwise & Lotus Notes have also been reported). This is a known issue in Microsoft Exchange servers – however, in the on-premise world, this is a setting that’s possible to configure. In the BPOS world, it is not.

What does it look like?

What do emails in Gmail look like when sent from the BPOS platform? See below:

Essentially, all content (text images, etc…) gets translated into a illegible winmail.dat file.

You read the same email inside of Outlook, using POP3, IMAP, or even the Google Apps Sync tool for Outlook, and the email looks just fine.

Technical Cause

The reason this happens is because BPOS servers default to sending email in a Microsoft-proprietary Rich Text Format called TNEF. And on the recipient side in Google Apps, this is only reported when mail flows through Postini / Google Message Security servers. In fact, when BPOS sends emails to retail Gmail addresses, the emails are interpreted just fine.

    • BPOS to Retail Gmail = Success
    • BPOS to Google Apps Gmail, no Postini = Success
    • BPOS to Google Apps Gmail, with Postini, email read via Browser/Default Interface = FAIL
    • BPOS to Google Apps Gmails, with Postini, email read through Outlook (POP or GASMO) = Success

Proposed Solution

Below is a proposed solution as posted on the TechNet blogs. We have attempted this, and worked closely with Microsoft and Google for a resolution, but there does not seem to be a known resolution at this time.

No resolution: Reply from Microsoft Online Services Support

Concerning your service request 100609-000749 thank you for the message header. I appreciate it. I researched this issue further and unfortunately, the issue why you cannot receive e-mails sent from a Microsoft Online company is that TNEF data sent by our servers is not supported by Postini, your message filtering service with Google. TNEF data is not a ratified standard data format for message data by the RFC organization. The best point of contact will be Google and see if they can enable support for TNEF data on your filtering service.

Issue Workaround:

• Due to TNEF data not being supported by Google, BPOS users sending to Google e-mail account is not supported.
• Please contact Google to discuss enabling TNEF compatibility on your Postini filtering service.
• Migrate completely to Microsoft Online will resolve issues also.

No resolution: Reply from Google Apps Support

This is a known issue with the TNEF format messages in Gmail shown as winmail.dat attachments (sans search will bring up a lot of results). The solution is not to send messages using TNEF format to Gmail recipients.

It is impossible for Gmail to fully support TNEF format since limited information about this format is disclosed. As the MSFT support puts it: “… TNEF data is not a ratified standard data format for message data by the RFC organization …”

You will need to open a support request with Microsoft Online Services to configure these settings. Actually I found this post online about the similar issue:


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