Thunderbird email client, trouble sending large emails

This problem also appears to have been mentioned before, but with no resolution.

I was unable to send a large email with attachments through Thunderbird, until I set the firewall to ‘Allow All’ traffic. I tried turning off the advanced security checks (mentioned in an AVG thread), but that didn’t help. Any advice?

What version of CPF have you been using? do you still have this problem with BETA?

Comodo Firewall

I think your problems with firefox are related to ICMP fragmentation needed messages. Can you please try the BETA release available at,1047.0.html

This version has the default rule you need. Let us know if it fixed your problem.


After upgrading to the Beta version, I am able to send the same large email that earlier would not complete. So, it appears the Beta version of CPF ( BETA) has resolved this issue for me.

One thing that may or may not be CPF related… I uninstalled 2.2.whatever and upon rebooting, I was missing \windows\system32\hal.dll
This also happened yesterday just after installing the Antivirus product and having a complete scan hang.

I still have other issues that I’m diagnosing, including the Antivirus inbound email scanning issue causing password failures. I’ll follow up in other threads as needed.