Sending email postfix FROM problem

[Just2Bad]

Hello I tried many things I found but I'm unable to send any email since the FROM addresse is always root@hotsname and my email provider is unable to verify this email. FROM email should be myaccount@providerdomain.

I tried Alias in /etc/aliases, tried with smtp_header_checks file to no avail

I need help to solve this

 

[Just2Bad]

status=deferred (host smtp.xxx.net[xxx.xxx.xxx.xxx] said: 451 <root@pve1.xxx.net> unable to verify address (in reply to MAIL FROM command))
root@pve1:~# mail -s "Test" whatever@xxx.net