File name: 'winmail.dat' Virus name: 'ExceedinglyInfected'

Question

Everytime I send a zip file off via my corporate account the recipient gets this message back:

FILE DELETED

The original contents of this file have been replaced with this message because of its characteristics.
File name: 'winmail.dat'
Virus name: 'ExceedinglyInfected'

I zipped the file on my Mac using 'Compress '. I have done this many many times on personal accounts. I am using Office Outlook via the web to send files. I'm stumped because a Google search doesn't reveal any easy fixes.

Answer 1

While it is not impossible that some malicious program is actually including a virus in your outgoing mail, the other likelihood is that your corporate network has a mail filter that prevents certain types of attachments. winmail.dat is basically Microsoft Outlook's catch-all container format for rich text and, I think, OLE objects (such as attachments). It might be detecting the ZIP file within the OLE container and blocking it. This is standard practice for corporate networks in many environments containing proprietary or sensitive data.

You could try these instructions from Microsoft to alleviate the issue, but since you said you are using the web client (Outlook Web Access?) the instructions might not be applicable to you.

Answer 2

Many corporate email systems block incoming and/or outgoing zip files for security reasons, so it may be that your corporate mail server just uses an unhelpful error message when doing so. You should first try talking to your IT staff to see if there is a sanctioned way for sending out zip files, but barring that, you can try possible workarounds like renaming the .zip extension to something else, or perhaps using a less well-known archive format, such as 7-Zip's 7z format.