Strange mail error

SYSTEM INFORMATION
OS type and version centos 7 min
Virtualmin version 7.0

trying to send mails with thunderbird the thunderbird show that error:

Cannot connect to SMTP server 2a02:1388:14b:7ffe:a00:27ff:fe8d:32c3 (2a02:1388:14b:7ffe:a00:27ff:fe8d:32c3:587), connect error 10061.

why

nikos

email account SMTP settings in thunderbird probably… this ip doesn’t seem to host any services.
looks like a typical ISP ipv6, so you’re probably using your own pc/mobile as SMTP, not the correct MX host.
so check that first…
Thunderbird account settings → Outgoing host (SMTP) and choose/add your proper SMTP host details.

could also be issues with firewall, hosts file, et others…

yes for the moment i am using a centos 7 minimal on virtualbox i will see when i will rent a server