Outlook 2007 and Avast

Hi all
Not sure if anyone can help but I’m running Outlook 2007 and the latest free version of Avast.
Basically, I can receive email to Outlook (via POP3) and when I send the email it leaves Outlook, but never arrives at the recipient. Incoming and Outgoing connection details are the same. I’ve also set up Thunderbird using the same credentials and Thunderbird sends the emails no probs and they’re received by recipient.
Anyone have ANY idea what could be going on here? I’m at a complete loss about what to try next as there are no error messages anywhere in Outlook and I just can’t find anything else besides Avast that could be stopping them.
Many thanks

Have you tried turning off Avast and seeing if Outlook will send that way? If it doesn’t, then it’s something in your Outlook setup. Otherwise, it could be a firewall setting blocking the application from sending out.

What avast version are you using 4.8 or 5.0 (home/free or Pro or AIS versions) ?