All, behind the scenes we have had Grant Taylor and Tom Ivar Helbekkmo helping us find a solution to the TUHS list DKIM issues. We have been running two separate lists (unmangled and mangled TUHS headers) for a few weeks. It looks like we can now merge them all back together and use the settings on one to avoid (most of) the DKIM problems. So that's what I've done: merged back to a single TUHS mailing list. I've restored the [TUHS] on the Subject line as well. I'll monitor the logs for further bounces. Fingers crossed there won't be any further unsubscriptions from the list due to bounce processing. If there are, I'll manually put you back in. Cheers all & thanks to Grant and Tom.     Warren