postfix refuses to transfer mails from 2 domains to exchange server

[m4rtin]

Hallo, I've got a postfix MTA running on an opnsense (with sensei and rspamd). It transfers to an Exchange 2016 Server. For weeks it seems everything is fine but mails from 2 domains were not transferred. First I thought it was the spamfilter, but when I deactivated the MTA and deliviered directly to the exchange server, all the testmails the sender of one of the domains sent, were delivered. I don't know where the error can be. It seems that postfix refused to deliver from the 2 domains, one of the 2 domains is a big company. Do you have an idea what might be the issue?

[Fright]

Hi
it may be a transport issues, it may be related to the restriction settings etc. need to look at the logs