Woke up this morning to directadmin blocking new email from Office 365 exchange.
The following error was being reported to the sender via Non Delivery Report (NDR):
550 5.0.350 Remote server returned an error -> 550 Email blocked by NJABL – to unblock see http://www.example.com/
In this instance we found a default setting within exim.conf that ships with directadmin to be responsible for this. There was a section to deny based on the presence of an entry in the NJABL blocklist – which has been defunct since 2013. While this effected Office 365 users, it didn’t seem to bother gmail at all.
To resolve this issue you’ll need to edit your /etc/exim.conf file.
Look for the following entry:
deny using njabl
deny message = Email blocked by NJABL – to unblock see http://www.example.com/
hosts = !+relay_hosts
domains = +use_rbl_domains
!authenticated = *
dnslists = dnsbl.njabl.org
Simply comment out these lines with a “#” symbol, restart your exim service with the command “services restart exim” and the problem should be resolved. Let me know otherwise and I’ll troubleshoot with you.