Mail not working?

[joximu]

you should not use the same hostname/domainname in mydestination (this is set to $myhostname, $mydomain, which is frede92.lir.dk, frede92.lir.dk.local) and in virtual_mailbox_domains:

you cannot use frede92.lir.dk in ispcp as a domain name or you need to give you host (at least for posfix) another name. If lir.dk is your tld, then add another hostname in front (e.g. frede92.lir.dk -> ispcp.frede92.lir.dk). Change this also in main.cf from postfix.

And please don't use the same hostname (FQHN) with two servers... you also don't like it when you have to talk with your double...

then try to connect to port 25 and have a look whats happening in the log.