Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Ok so the title pretty much says it all.

We are offering a Hosted Exchange solution for our customer. Everything is working fine except for one customer complaining that he is receiving winmail.dat or winmail.txt attachments instead of the actual Word Excel or PowerPoint attachments he should be receiving, only when these messages come from a specific European senders, that is using Lotus Notes.

I know that usually the problem is coming from Outlook senders to other mail clients, but this is not the first they inform me of this but I can't find anything on the matter so far.

Has anyone ever gotten and solved this problem? If not, does anyone have any idea regarding this?

I had solved this problem a few months ago, by upgrading Outlook to SP2 and then uninstalling it using the Service Pack removing tool of Microsoft. It seems that only the latest SP1 version could work but not the SP2.

The problem is that now nothing is working at all.

Thank you for your help,


share|improve this question
Which version of Outlook? – Massimo Dec 18 '13 at 20:04

The little I know of this issue is that this happens normally when someone with Outlook Client sends an email in "Outlook Rich Text" format. (Available to change from Tools|Options| Mail Format|Internet Format).

A non-Outlook client can't read this and just has an email with winmail.dat as an attachment.

We fixed this for people by making the default "Internet Format" on all the clients default to "HTML" if the original was Outlook Rich Text.

In your case one of 3 things is happening perhaps:

  1. The company with Lotus Notes are sending their emails out in some form of "Outlook Rich Text" that is broken.

  2. The Oulook clients aren't reading Outlook Rich Text format?

  3. They are using the "Send as Email" option within Excel/Powerpoint which might generate an Outlook Rich Text email that lotus notes can't handle. Get them to create new mail in Lotus and attach the Excel file like a normal email.

This is not really an answer, but may be useful to narrow it down.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.