In other cases, the receiving client (Apple Mail) does not use or recognize the winmail.dat file. During transport, the content of the message may be changed, preventing the receiving client from being able to read the formatting Outlook uses it when sending a Rich Text-formatted message. The Winmail.dat file is used to preserve Rich Text formatting.
In my view, the likely cause is that the Office 365 Exchange instance isn't respecting the encoding preferences in the Outlook 2016 client - in which case it's a Microsoft bug.
Instance already had this setting, but the problem persisted. The obvious fix is to use the "default" rule to set "use rich text" to "Never" - although in our case our Exchange Of course, you'll need to add each domain individually if you have lots of recipients with the winmail.dat problem.
#Winmail reader windows 8 plus
#Winmail reader windows 8 mac os x
The problem: Some email recipients on Mac OS X using Apple Mail and Gmail receive winmail.dat attachments in place of correctly-encoded MIME attachments from users running Outlook 2016/Windows 10/Office 365 hosted mail.
We appear to have found the solution - which I'm posting here to (hopefully) save some other poor b*stard from having to wade through weeks of poor documentation, support calls and forum posts. Two separate tickets raised on two Help Desks. It would be nice to actually get some forward progress on this - so far, this is the third Microsoft forum I've logged the issue with, and there have been 2056, and a check reveals that it's the latest version - no newer updates are available. There are no problems sending attachments from the offending account using OWA There are no problems sending attachments from Outlook 2016/Mac to the problematic Gmail/AppleMail account There are no problems reported from any external recipients using PCs, irrespective of mail server platform (including Gmail)
#Winmail reader windows 8 Pc
The PC user is able to send attachments to other internal Exchange-based accounts without problems, and no errors occur when internal Mac users read the messages using Apple Mail We only have one PC running Outlook 2016 (all other users are on Mac) I've run the (I can't insert the link because of yet another Microsoft account mess-up) fix twice to no avail on the Microsoft-hosted Exchange instance. We're getting persistent problems with one of our users sending attachments from Outlook 2016/Win 10 to a client on Gmail/Mac OS10.10/Apple Mail, where all attachments appear as the dreaded winmail.dat files. This has now persisted for more than two months, and our company is increasingly looking like clowns in front of our customers. I've been bounced to this forum from the Office 365 forum, to try and get a resolution to this persistent winmail.dat issue.