Multiple Domains in Central Email - Mails can only received for the existing domain, but not for the three new domains

Hi,

I've a problem, I can't find the solution.

A client of me has a Sophos Central in use and told me, that they must have three additional web-/mail-domains.

So I added the domains in Sophos Cental Email like the first domain, which works fine, they are verified and so on each for each, exact like the first mail domain.
But no email is received, in the message history Board they doesn't appear, but of course the one of the main mail domain.

I don't receive an non-delivery-Message from my mailserver, in the mail queue I can see, that the mails is sent.

Whats going wrong?

Alex