[quote user="Tim W Young"]I think that solved it![/quote]

Good to hear! 

Hi! 

I'm running the latest beta Mercury (v4.81.187, Nov 18 2018), using MercuryS, MercuryE, and MercuryI.

I have the "Only send delivery notifications to local users" setting checked (in "Configuration/Mercury Core Module Configuration/Mail Queue/Queue Processing Controls").  However, my server is still apparently generating backscatter.  (I have become listed again at www.backscatterer.org.)

Any ideas? 

Btw, to any users out there who are new, you should get set up with mxtoolbox.com to help monitor the health and blacklistings of your server.

Thanks! 

Configuration/MercuryS/General  - ensure "Accept mail for invalid local addresses" is unchecked

Otherwise you may be sending a rejection message to the incorrect sender 

Unfortunately it's already unchecked.

Do you know what messages are getting you listed?

Virus/spam rejections? Autoreplies? 

Unfortunately none.  I've received the odd dmarc report, but no subject or body details.

According to their website they collect information from 'honeytrap' email addresses.

I don't know what your outgoing mail count is like, but doing some monitoring of the logs would be my next step, as well as double checking that there's no other device or software that could send out mail directly. 

I only have four local user accounts, and one of them never logs in.  So far everything in the logs seems to be okay.  All accounts require authentication and encryption, and have good, complex passwords.  The rest are just aliases, of which I have 71.  Just in case, I'll have all of the users change their passwords.

I've cleared out a pile of the aliases, so hopefully that will help as well.

I think that solved it!