Unable to verify sender while sending through Spamexperts

[bway]

We trying to fix a problem with one of our servers.
The message system of Directadmin can't send mails, we get the following error in the Exim mainlog:

SMTP error from remote mail server after MAIL FROM:<username@hostname> SIZE=1751 AUTH=username@hostname: 451 unable to verify sender

In the Exim.conf we disabled the 'verify sender' option.
Spamexperts doen't really have any options to disable/enable.

We are running out of ideas to try.

 

[Zhenyapan]

"error from remote mail server" - you can't disable it on receiver side if you haven't access to it.
you as sender must provide all info to pass verification (smtp auth/spf/dkim/rDNS/dmarc).