My company is using Exchange 2010 through Office 365 as our e-mail platform. From time to time users will complain that when they send a message containing an attachment to an external user that user will receive the attachment as a winmail.dat file which they cannot open.
From my research, I understand that this is because Exchange is sending the message in TNEF format which other mail clients do not understand.
I know that I have the option of telling Exchange to never send messages to remote domains in TNEF format, however before I do that I want to better understand the implications of doing so.
TNEF encoded attachments are used to send:
The formatted text version of the message (font information, colors, and such)
OLE objects (embedded pictures, embedded Office documents, and such)
Special Outlook features (custom forms, voting buttons, meeting requests, and such)
Regular file attachments that were added to the original message
Does this mean that if I globally disable TNEF for all remote domains that mail will be sent as plain text only (i.e. no text formatting, images in signatures, etc)? Also, does it mean we would not be able to send Outlook calendar invites to 3rd parties?
I have seen differing opinions on this.
As far as mail formatting, some claim that disabling TNEF will cause messages to be sent as plain text while others claim that they will be sent as HTML.
I am looking for some references that better explain the ramifications of disabling TNEF.