URGENT: how to change machine hostname??

[wallmapu]

For some reasons email keep being sent from panel.mydomain.com. I wish to change that to just mydomain.com or not even that just have control over it. I tried modifying /etc/hosts, /etc/hostname, and main.cf changing every entre from panel.mydomain.com to just mydomain.com, to no avail.  This is urgent.

[Me.B]

check postfix config under /etc/sentora/configs/postfix
file main.cf

[wallmapu]

check postfix config under /etc/sentora/configs/postfix
file main.cf

I changed $mydomain and $myhostname to mydomain.com,

I have modfied /etc/hostname

I have modified /etc/mailname

I don't know what else to do.

the panel subdomain keeps showing up in the header and mail keeps getting caught in spam folder in gmail  and hotmail, despite having 10/ on mail-tester.com

[apinto]

The emails being sent from panel.domain.tld is not elegant.
However it hardly is the cause of the email being sent to the spam folder.

[wallmapu]

The emails being sent from panel.domain.tld is not elegant.
However it hardly is the cause of the email being sent to the spam folder.

The hostname panel.mydomain.com doesnt match the spf verified hostname mydomain.com. i cant say with certainty this is not the cause of my mails being labeled as spam because so far i hve ben unable to change the hostname to try the other way.