Slow IMAP connection with Comodo Firewall

Hello,

I am trying Comodo Firewall and experience a strange behavior. It seems that the connection to a IMAP mailserver in my netwerk slows down enormous. After the connection is established everything is fine. It occurs with several mail clients and the problem disapears when I shut down the Comodo Firewall.

I tried this: https://forums.comodo.com/help/slow_choppy_email_traffic_with_thunderbird_and_comodo-t4330.0.html
but that doesn’t help me.

Can you advise me what to do?

regards,

PieterS