Just my 2 (euro)cents:
After an update of Avast Home a few days ago I got on our laptop (XP sp1, Outlook2k) the following error:
Protocol: SMTP, Server Response: '421 concurrent connections limit in avast exceeded', Port: 25, Secure(SSL): No, Server Error: 421
Not on my main machine. Also my dauther suffered from the same error on one of her machines.
I couldn't find a good solution (at that time, just saw the parameter in the .ini file
.
My solution was: download the newest version. Disconnect from the net. Uninstall Avast. Reboot.
Install the newest version. Reboot. Back to the internet. Update.
And worked like a charm.
Could something have gone wrong with the automatic update?
BTW both my and my daughter's machines live behind a Smoothwall so no firewall on our machines.