* Robert Eisig [05-04-17 17:07:37 +0200] wrote:
but i don't have a domainname here because i am sitting
behind a dialin-connection. and if i use gmx.net, the mail that is
received has a message id ending with @gmx.net - which makes sense in
my eyes. correct me if this is stupid.
Of course it is (technically) trivial to add any host to a message id.
But usually you need permission to make use of one. If you don't have
one, you have two options: (1) try to send mails without the message id
or (2) look for someone who'll give you a FQDN (=fully qualified domain
name). For the latter, there're many services providing them for free
(for a FQDN you don't need a host which is existing or reachable, just a
unique name within a domain you have permission to.)