"Since installing the new free version, Outlook has started putting a second email in the outbox, with no "To" (Unless it's one that has a name attached - eg. Ian Shere [firstname.lastname@example.org]), no subject and no body. It, obviously, won't send, but the outbox gets filled up with them.
I have checked that it really is Avast by disabling Outbound Email Scanning and it doesn't happen."
Yep - exactly the same experience here. The forced workaround is to disable scanning outbound mail (just unchecking "Insert note into incoming clean message" alone doesn't fix the problem for me as suggested by ). Windows 7 64-bit Outlook 2010. No answers from Avast! at all. Silence is a bad policy on their part. I'd rather hear "We're aware of the problem and working on a solution" than being totally ignored.