[Dovecot] self-signed certificates

[Benjamin]

Hallo,

i'm having troubles installing self-signed certificates for dovecot.
After installing, dovecot generates a key and cert. But he is using the 
wrong common name (where does dovecot get this name from?). I tried 
deleting them and installing a handcrafted cert with this:

openssl genrsa -out mail.key 2048
openssl req -new -key mail.key -out mail.csr
openssl x509 -req -days 4312 -in mail.csr -out mail.cert -signkey mail.key

after that i tried to update the dovecont.conf to point to the new 
files. But dovecot refuses to read them, i allways get an error, that 
dovecot can't read the certificate file.

With dpkg-reconfigure dovecot-common, dovecot generates new ones, and 
they are working fine, but have the wrong common name.

Thanks in advance
Regards Benjamin