Avast 7 Web Sheild can prevent Outlook 2010 from sending mail.

Avast Free Antivirus / Premium Security
1

I’ve installed Avast 7 on a friend computers (Windows 7 Ultimate 64 bit SP1) who uses Outlook (2010 Pro Plus 64 bit) for email. I wasted hours assuming the problem had something to do with encryption settings or the Mail shield. Finally I simply enabled the shields one at a time until the problem occurred and found it was the Web Shield that was to blame.

Disabling Web Shield works, but so does going into expert settings and checking “Scan Traffic from well-known browser processes only” …

His email provider’s setting have him using port 80 for outgoing mail, which I’m guessing caused Avast to think Outlook was a web browser?

I’m sharing this because.
a) It may not be the best solution.
b) This information might help someone else.

2

Well the Web Shield shouldn’t get in the way for sending emails.

I suspect that you are using an http port (probably port 80) for sending your email in the Outlook account settings ?

Using an http port results in the connection being redirected through the web shield proxy and it is rightly expecting HTTP protocol to be used on what is an HTTP port, so it would fail as it would be using SMTP protocol.