before we handed over domain_name instead of domain_id to the checkDomainModuleDomain function,
which resulted in nothing. This fixes the call by querying the database for the domain_id for
the given domain_name.

The dkim_select can start with a number, but has to contain atleast
1 letter and has to be between 1 and 63 characters long.

before the regex matched empty entries and entries starting with a number.

UI is still to be implemented