[IMail Forum] Max message size limit for domains you relay for

[Heimir Eidskrem]

A client that we are relying email for is getting this error when people 
send them large mails.

Body of message generated response:
552 5.3.4 Message size exceeds fixed maximum message size
I can't find where I set the limit for those domains that is NOT listed 
on the server.

I am missing the obvious?