Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I am experiencing a strange problem when receiving email attachments.

The files are valid XML files, but they have the file extension .usf or.xif.

When the emails are opened in Outlook and the attachments are saved, the file extension is changed to .xml?

I am using fastmail.fm as my server.

The senders are using webmail or Thunderbird.

Is this a problem with the sender, fastmail or outlook?

share|improve this question
add comment

1 Answer 1

My guess is that it's Fastmail. I tested Thunderbird and Outlook using the scenario you outlined, and the file extension was not changed.

It seems that some vulnerabilities were exposed in Fastmail earlier this year (this and this), and it's possible that .XIF and .UFS have been identified as executable file formats, or dangerous for other reasons.

share|improve this answer
    
We logged in to Fastmails webmail system and the attachments had the original extension. –  William Macdonald Dec 7 '12 at 10:49
add comment

Your Answer

 
discard

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.