As I'm not sure which component is doing this I've moved the thread to Livesafe anyway for possibly better support. What mail client are you using?
Here's hoping that Livesafe uses the same interface as my All Access/Total Protection.
Something to try would be to disable email scanning in SecurityCenter > Virus and Spyware Protection > Real-Time Scanning > Settings > uncheck Email Attachments and click Apply.
Many thanks for your reply and for moving the thread.
I've tried what you've suggested but unfortunately it hasn't solved the problem.
Are you by any chance using Thunderbird for mail?
There are known problems with that and Technical Support are the best people to help with this. It's free by phone or online chat and linked under useful links at the top of this page.
Sorry I forgot to answer that! I'm using Outlook.
I'm assuming Outlook as against Outlook.com. Then all, I can suggest is make sure Outlook has full permission in Firewall > Settings > Internet Connection for Programs plus in Outlook itself make sure it has all its defaults. You do that be checking general defaults here: http://www.eightforums.com/tutorials/9173-default-programs-set-your-default-prog rams-windows-8-a.html and do the same for Internet Explorer while you are in there.
If that doesn't help then most definitely your best bet for support on this is Technical Support as I previously mentioned.