In: pop.gmail.com port: 995
Out: SMTP.gmail.com Port: 587
SSL checked.
Secure connection: TLS
okay, this just means that you never used the mail shield before. The only difference is that before, in previous Avast builds, the mail shield proxy was ignoring your settings, but now there's a bug. So you can either go on like before, by deactivating the mail shield which I certainly won't advise, or get it to work for the first time

>>> in Thunderbird: change 995 for 110 and set security to none
leave 587 but switch security to "none"
(this does just mean that Avast will do the ssl job >>>
the mail shield is also a proxy...see if it works now...it should, if not post back and we'll check your Avast settings