I installed 2.1.0.1 today to replace the Sygate Firewall. Everything works except I can not connect to one of my e-mail accounts if AVG E-Mail scanning is turned on. I am using Thunderbird 1.5.0.4 for the mail reader under Windows XP SP2 with all the latest updates. I can connect to my worldnet.att.net account and receive e-mail with no problems. I can not receive or send e-mail from my Cox Cable account. As this is my SMTP server it means I can not send e-mail unless I turn off the AVG e-mail scanner.
I looked at a number of other posts with similar problems but could not find any ideas that worked. I also looked at AVG’s firewall guide but Comodo is not in the guide 
It is strange that I can retrieve e-mail from ATT but not from Cox Cable.
G’day,
Welcome to the forums. These forums are very actively monitored by Comodo support staff (including the CEO - Melih!) and they are exceptionally responsive to users problems and suggestions.
Having said that, AVG email scanning is an issue and Comodo have admitted it’s got them stuffed what the root cause of the problem is (At least they’re being honest and upfront about it. ).
Further to this issue, I’ve noticed another odd thing with the version of Thunderbird that you’ve quoted.
One of my systems has six email accounts set up in TB and the passwords are all stored in TB’s Password Manager. Assume that I’ve turned off AVG’s email scanning and the Comodo Personal Firewall (CPF) is correctly configured and active. If I tell TB to get all mail, it might get them all or it might respond that the third, fourth, fifth and sixth accounts can’t be contacted because of a bad password. If I turn off the automatic login and password so TB will prompt me for each password, it works fine.
I’ve got a sneaking suspicion that the Comodo firewall is caching the previous password a little too persistently for TBs liking, or the firewall isn’t correctly detecting the required change of credentials when TB finishes checking one account and switches to the next.
Try turning off the automatic login temporarily and see if it’s successful on your system.
I’ve only recently installed CPF on this multi email account system after testing it on my test box, so I’ll be posting this as a separate topic.
Despite the multi account and AVG issues, CPF is still the best software firewall I’ve ever found and the support and user interaction of Comodo is unparalled (IMHO).
Again, welcome to the forums.
Ewen 
(WCF3)
I’ve got a sneaking suspicion that the Comodo firewall is caching the previous password a little too persistently for TBs liking, or the firewall isn’t correctly detecting the required change of credentials when TB finishes checking one account and switches to the next.
Try turning off the automatic login temporarily and see if it’s successful on your system.
I tried removing the password for the account but that doesn’t fix the problem
Will continue working with tech support to see if we can find a solution.
Thanks for feedback.
Just an update on my previous post. I noticed that even after rebooting Thunderbird that the second account did not require the entry of a password. After rebooting the computer it did require the password. So maybe some program is caching the passwords and this is causing problems. Whether the problem is with AVG or Comodo I don’t know.