Yesterday, I updated to your newest free version. Since then, I cannot send outgoing mail using Microsoft Outlook 2007 on a Windows 7 32-bit operating system. What’s causing the problem? How do I fix it?
You have to disable SSL protection in Mirosoft Outlook 2007. 
Hope this will help you.
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=842
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=917
I have outlook 2010. Was working fine until yesterday. I’ve gone into avast settings and disabled SSL (my smtpout doesn’t use SSL). Made sure the ports were the same. Also tried deleting and rebooting to auto configure. Outgoing still blocked. Only option is to disable scan of outgoing.
What I find interesting is that Outlook says “Sending 1 of 2” and yet there is only one email in the Outbox.
Try:
Avast main GUI → web shield → expert settings → well known browsers only.
In theory, web shield is not connected to email, but…
Delete the firewall rule, reboot, and run the program so the firewall can recreate the rule.
If these changes are not successful, change back the setting in the web shield.
My version doesn’t have the firewall tab but I changed the web settings and it seems to be working (didn’t reboot). Thanks!!
I don’t understand what’s changed though (other than perhaps an avast update in the last 2-3 days?). It only affected my pop account, not exchange.
For the first time in many years, I was and still think about replacing Avast by something that will allow my Outlook 2010 to send emails! I called Avast support, iYogi, who told me everything that is wrong about my computer, but noting about my Outlook problem without me paying for a minimum of one year of services.
I corrected the problem by removing the HTTP port 8081 from the list of scanned port.