> I honestly can't see how the mail shield gets involved unless you are using ports other than the http ports, e.g. ports that the mail shield would monitor (25, 110, 119, 143, and the secure email ports, etc. etc.).
Many thanks DavidR that seems to be the answer...
I don't get it. I've been running Avast for a couple of years now, and I haven't messed with the default settings in recent memory (if ever). On the Avast troubleshooting page, I show the following ports:
HTTP: 80,8080,8091,8081,8008,8888,3124,3127,3128
SMTP: 25,80
POP: 110
IMAP: 143
NNTP: 119
Yeah, there's a conflict between HTTP and SMTP. The 80 obviously doesn't belong under SMTP. I deleted it, and reenabled Mail Shield, and the problem seems to be gone.