Mail server and staff

Hello,

I'm new to this forum. I'm using CWP for one year now and I have a PRO edition.
My provider who gives me PRO says that we can't have mail incoming and outgoing server other than nameserver. Is that true?
When we was on cPanel, always for mail server was: mail.domain.com. and now it has to be nameserver.domain.com. Why's that?
Is it possible to make a VPS namserver with server.domain.com and for mail SMTP servers mail.domain.com?

Thank you!

You can set as hostname mail.yourdomain.tld and it will work both as hostname and for MailServer including SSL.

to me with mail the outlook does not accept me I have to use host.sample.tdl
And a question if you want to use it as IMAP then how would it be?

If you want to use SSL, then you have to use the hostname as the incoming and outgoing mail servers.

Haven't found a way around it with CWP, ISPCOnfig or iRedMail.
They all use the hostname for SSL. Must be something with Postfix and Dovecot.