I have a Exchange 2013 with a Firewall DLINK DFL-800 in front of it.
Some messages from the internet could not be received - they return to the senders the following error:
SMTP error from remote mail server after end of data:
host mail.phoenixy.ro [18.104.22.168]: 554 Transaction Failed:
Sender Email-Id is different from Display Email-Id
This is a Exchange error (from Malware scaning) or it is from the firewall in front of it ?
Thank you in advance,