Conexion error failed to reach the server after reply roundcube and usermin

SYSTEM INFORMATION
OS type and version Ubuntu Linux 22.04.3
Webmin version 2.101
Usermin version 2.001
Virtualmin version 7.8.2
Theme version 21.07
Package updates 2 package updates are available
impossible to reply o resend mails with html contens
i can send normally, and reply simple txt too
any idea??

No idea whatsoever you need to look at the postfix log use Webmin->System->System Logs Viewer normally like this

from there you should able to see what is happening, but you haven’t told us which email client you are using, that could be helpfull.
I tend to, if I get an email problem, test the problem out using usermin, if you can send from usermin with no issues the problem will lie with the email client you are using.

i am going to look, i try with usermin and roundcube, roundcube when you press “send” after replay and etc, give error, if i try same shem in usermin, it work , but send mail empty, w/o subject

Have added any mail filtering in usermin ?