Email client issue

Hello Ian,
I understand the inconvenience caused. I am sure we will be able to fix this together. Yes, I request you to change AVG Firewall network profile to private (open AVG Internet Security > menu > settings > components > firewall > customize > network profile > change all the network public to private) at first, please go to Firewall customize settings again > scroll down > click on system rules > enable all the system rules if it's not configured, please click OK and check if you can access all the websites with enabled AVG Internet Security. If the issue still persist, please disable AVG component one by one and check which component is causing this issue.
Best regards,
Alok.

I use the Thunderbird (Mozilla) email client, whenever I try to send e-mail, the client reports the server detected it as spam and blocked it. If I turn off AVG the problem doesn't exist, is there a setting to overcome this?

Hello Ian,
I understand the inconvenience caused. I am sure we will be able to fix this together. Yes, I request you to change AVG Firewall network profile to private (open AVG Internet Security > menu > settings > components > firewall > customize > network profile > change all the network public to private) at first, please go to Firewall customize settings again > scroll down > click on system rules > enable all the system rules if it's not configured, please click OK and check if you can access all the websites with enabled AVG Internet Security. If the issue still persist, please disable AVG component one by one and check which component is causing this issue.
Best regards,
Alok.