It should be capable of blocking unauthorised outbound Internet Connections.
In sending email through a firewall avast's Internet Mail provider makes no distinction between good email and bad email, it helps them all get through because it does not recognize any email program.
So, to stop a spambot it is necessary to turn off all mail scanning by avast and deny permission for ashmaiSv.exe at the firewall. Unfortunately even this may not stop the spambot if (as is so often the case now) it is hiding behind a Windows service that needs outbound permission to do its job.
If this poster wants to know the service that is sending the spam email then it would be best to create (for a while) a more detailed avast! log of the mail connections. This must be done
before the steps I have mentioned above.
You can get the mailscanner to log your connections by editing the avast4.ini file (in Program Files\Alwil Software\Avast4\DATA folder).
In the section headed:
[MailScanner]
add the line:
Log=20
and save the updated file.
Allow a little time for the spam to record in the log.
The log will be in Program Files\Alwil Software\Avast4\DATA\log\ashmaisv.log
Before posting the log you should mask any personally identifiable information.