- iRedMail version 1.6.2
- Deployed with downloadable installer
- Linux Debian 11
- MySQL
- Web server Nginx
- Opensource

Setup is done with IPv4 and IPv6 using self signed certificates. Our mail seems to be working fine from the browser(Sogo). The issue comes when trying to use a mail client like Thunderbird. When Thunderbird is trying to grab the cert over IPv6 it times out.
I've run the following command which defaults to use IPv6.

time openssl s_client -showcerts -servername <server> -connect <server>:465 <<< "Q" | openssl x509

with response in
real    2m10.987s

Then I tried the same thing but pointed to the IPv4 address

time openssl s_client -showcerts -servername <server-ipv4> -connect <server-ipv4>:465 <<< "Q" | openssl x509

with response in
real    0m0.064s

I've tried adding the following below into /opt/iredapd/settings.py and /etc/postfix/main.cf
mynetworks = <added in my networks>

main also showing
inet_protocols = all        (enable IPv4, and IPv6 if supported)

Any help here or suggestions would be greatly appreciated