Change SMTP Port (Cyberpanel and SnappyMail)

Is there clear instructions on how to change the default SMTP port?

example: most hosting providers Block ports 25,465 but leave port 587 open

I would like to force cyberpanel to be the mail server port 587 to send email.

but how to do this and ensure snappymail sends with this port too?

in cyberpanel at mydimain.com:8090/email/listEmails

Port 25,587 and 465 are listed but ofcourse I only want to use 587 as default

I current guide or just how to instructions would be handy for everyone trying to send email thru hosts that block outbound email