Why is downloaded email disappearing immediately?

I get variations on this question all the time. The symptoms in this example are actually rather mild - much more
common are mails that are downloaded and then immediately disappear. It can also happen across a wide variety of email programs as
well.

There is a common thread, though. In fact, the question above alludes to it. (And it has nothing to do with the color of your
face .)

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It's very possible that anti-virus, or rather anti-malware software is at fault.

The problem is that many anti-malware packages - particularly the security suites that try to do many things - often include a feature whereby they will scan email as you download it. There's really no facility for this kind of intrusion built into the way that email is handled, so different anti-malware tools insert themselves into the process in different ways.

Sometimes those "different ways" can interfere with what your email program is expecting. You may end up with that classic computer phrase "unexpected results" - which is just a fancy way of saying "we don't know what'll happen, but it probably won't be good".

The good news is that most anti-malware tools allow you to control whether they scan email, and often just how intrusive they should be. In other words, you can turn it off.

The bad news is that there's no common terminology to look for.

If you're experiencing problems with missing messages or for that matter any kind of odd behaviour with your desktop email program, one of the first things to do is to fire up your anti-virus and anti-spyware programs and look for options related to email processing. Terms to look for include "email", of course, but also thing like "phishing", "scam", and perhaps technologies like "POP3" and/or "IMAP". It's worth spending a few minutes with the documentation for those programs to make sure you've got the email-related services turned off.

In fact, I heard back from the person who originally posted the question above, and sure enough...

Now, it's natural to ask "am I putting myself at greater risk by turning off my anti-virus program's email security features?"

Yes, no and maybe.

First, realize that I recommend turning them off as a diagnostic step. If doing so doesn't resolve the problem you're having, then after all is said and done (ideally after the problem is resolved), feel free to turn them back on.

Second, in many cases active email scanning is somewhat redundant, or can be accomplished in other ways. For example, scanning attachments can be done on disk after your email has been received, and may even be caught by a regular full disk scan - the only difference being timing.

Finally, all the protection in the world is no substitute for common sense and education when it comes to email. Even when on, you still need to remain vigilant to avoid the latest malware, phishing attempts and scams.

Personally, when offered, I always turn off intrusive email scanning in any malware tool I use or manage, both to avoid problems and to reduce the complexity and potential for performance impact.