Read receipts being marked as spam by MS

The most recent version of MailScanner contains a new feature called watermarking which is designed to prevent so-called backscatter bounces from joe-jobbing. Joe-jobbing is when a spammer sends out email from a spoofed email address on your server. The spam was not actually sent from your server, but your server receives the bounces from these spams.Watermarking in MailScanner adds an encrypted ‘watermark’ to each mail sent through your server, and any legitimate bounces (emails with a null sender) should contain this watermark. If a bounce does NOT contain the watermark, it is marked as spam. Unfortunately there is a bug in this system where read receipts from certain mail programs, which are sent with no sender so they look like bounces but they do not contain the watermark, are being marked as spam by MailScanner.Until this bug is fixed in MailScanner, if you are experiencing this problem we would recommend that you disable the watermarking feature. To do this, in the MailScanner configuration go to the section called “Watermarking” and set the options Use Watermarking, Add Watermark, and Check Watermarks with no sender to no, then click Change.