You wouldn’t expect a spam filter to have such strong emotions, but some faulty code in the popular server side spam filter Spam Assassin caused that filter to mark any email sent in 2010 as spam. Good old Waxy was the first report I saw of this. Spam Assassin has already released a patch to fix this bug, but of course that requires server administrators to implement it.
So what should ministries do? Spam Assassin is fairly popular so lots of un-patched servers out there could cause deliverability issues, but by this point any decent IT department would have already patched the issue. Especially since it would mark any message sent in 2010 as spam, including normal business correspondence.
However, it is possible that some smaller internet service providers may be behind the curve, so it is worth monitoring for the next few sends. Watch your bounce and delivery rates, and if you see a dip explore further. Check to see if most of your undelivered messages are to a single email service provider, you can tell by looking at the part of the address after the “@.”
For example, if most of the undelivered email was to emails @masterworks.agency, it might be that Masterworks hasn’t updated their software (for the record we don’t use Spam Assassin and if we did we have great IT people so we would have the patch installed). If you see a problem, search for that domain on the internet, get their information and give them a call, you can reference this post and see if they do indeed have an old version of Spam Assassin.
Overall I expect the impact on deliverability from here on out to be minimal, but if you did a big send, in the first few days of the new year, you may want to look at your numbers and if they are off, do a selective re-send to just those people who didn’t open.