MS exchange (cloud) creating winmail.dat attachment for some external users

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robjg63

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#248920 16-Apr-2019 09:46

So we moved to office 365 mail quite a while ago. I just recently learned that some users have issues receiving emails with attachments etc.

They can see the plain test body of the email but any attachments etc are bundled into a winmail.dat file as an attachment.

Seems normally to be an issue with icloud and gmail recipients.

After spending a couple of hours with dooctor google, I found that the problem is when some mail is being sent it will be in rtf format (rather than html).

I suspect that sometimes even if the user sends in HTML the mail server is converting it to rtf.

Anyway - I created a 'remote domain' for icloud and changed a setting 'use rich-text format' to Never.

This seems to have fixed the problem when sending to icloud users - but I dont want to set up lots of remote domains.

My question is - Is there any downside me just changing the 'default' connection to 'never use rtf'?

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

MackinNZ

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#2217987 16-Apr-2019 10:14

You can solve this with a PowerShell command:

Instructions here

Actual command is: Set-RemoteDomain Default -TNEFEnabled $false

nathan

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#2217995 16-Apr-2019 10:30

What are the remote email client apps that are creating those DAT files?
Is it Outlook, which version?

robjg63

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#2218022 16-Apr-2019 11:01

We have a small user base with around 8 users that use MS Outlook 2016 installed on windows 10 PCs.

The other users (around 20) use webmail or apps on their phones.

I dont think the emails are being sent by default as rtf - Normally they default to HTML - so it looks a bit lik ethe cloud exchange server is maybe converting them to rtf and creating the winmail.dat file.

My question was - If I change the default 'remote domains' to 'never use rtf' - does that have any downsides?

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

robjg63

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#2218026 16-Apr-2019 11:04

nathan: What are the remote email client apps that are creating those DAT files?
Is it Outlook, which version?

Sorry - Remote clients... I tested it yesterday on a user that has an apple icloud account.

Was viewing the email in a web browser.

Mail seemed to be created as HTML.

Arrived with winmail.dat file in the icloud webmail.

When I created a remote domain for icloud.com with 'never use rich-text' and sent the mail again it had the attachments all looking normal.

Have also had the odd compliant from a couple of gmail users - but the icloud one above was easy to test and see the results.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

bagheera

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#2218041 16-Apr-2019 11:27

The only time I have problem with winmail.dat is because of RTF, not HTML, changing to HTML always fixes the issue. Do you put a footer on all mail going out? ie something like "This email document and attachments are confidential to our organisation and subject to legal privilege Bah Bah Bah" type thing - have had this making html format at the client side be RTF after going through the transport rule when it adds it.

robjg63

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#2218051 16-Apr-2019 11:40

bagheera:

The only time I have problem with winmail.dat is because of RTF, not HTML, changing to HTML always fixes the issue. Do you put a footer on all mail going out? ie something like "This email document and attachments are confidential to our organisation and subject to legal privilege Bah Bah Bah" type thing - have had this making html format at the client side be RTF after going through the transport rule when it adds it.

Yes - we usually have footers. Could be something like that. I dont know what format a signature in MS outlook uses.

But as above - is there a downside in just getting the mail server to never use rich text for all remote domains?

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

bagheera

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#2218070 16-Apr-2019 12:13

robjg63:

Yes - we usually have footers. Could be something like that. I dont know what format a signature in MS outlook uses.

But as above - is there a downside in just getting the mail server to never use rich text for all remote domains?

not that I have come access, just the upside of all the none rtf mail servers/clients can now read the mail.

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ANglEAUT

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#2219497 16-Apr-2019 23:05

robjg63: ... I dont know what format a signature in MS outlook uses.

Outlook creates three formats of the signature and saves them in the users APPDATA folder, HTML, RTF & TXT. Outlook chooses whichever file based on the format of the mail & rules for what type of mail the recipient can receive.

robjg63: ... But as above - is there a downside in just getting the mail server to never use rich text for all remote domains?

No, there is not a downside.

Exchange servers are practically the only servers that can read the Winmail.DAT file. There are many non-Exchange servers out there.
These days, only hard core users use text only email clients. The avg Joe has an email client that can display HTML; think Gmail & web browser

Please keep this GZ community vibrant by contributing in a constructive & respectful manner.

robjg63

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#2219525 17-Apr-2019 07:32

Excellent!
Thanks for all your replies.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler