can't email large files

I appear to be having a problem with COMODO disrupting outgoing emails with large attachments. For example, I tried to send a 7 mb file, and the transmission was not completed. Smaller files mail just fine. An error message appears, something to the effect that my smtp server is not accepting the mail. This occurs despite having the “scan outgoing emails” disabled, and that there is no problem with the smtp server. In fact, the only way I was able to successfully send the email was to Exit or turn off completely COMODO. I am using Thunderbird as my email client, so perhaps there is a conflict with COMODO. I have reviewed all the various setup features, reviewed the issue through the help feature in COMODO, and checked this forum. Is there a way to fix this issue? Thanx for considering.

Same here when over 1mb,with or without attachments.Outlook Express & Road Runner.Note breaking up email may send @ times but receivers read it as scrambled.

Firstly, have you ticked the box in Thunderbird settings that enables easier detection of viruses by antivirus software?

It comes under privacy settings I think.

Are you using a firewall? If it is Comodo Firewall then you may need to skip advanced security checks and allow invisible connection attempts for ‘CavEmSrv.exe’ in the application monitor settings.