Thanks Tim. Yes, that's correct. Only few users have set messagng preferences and only one has set messaging as a preference ofr subscribed forum posts.
Further invistigations have narrowed this down to the config table and my colleague has been through the painstaking task of eliminating by comparing and changing values. After changing all probable options he started on the those less likely to have any effect.
The site is now sending out emails from forum posts... the value that needed changing to bring this about...? The support email.
That doesn't make any sense to us:
- It's been the same email since the site was installed
- The site has functioned correctly with the same email in place since its upgrade to 2.2.x
So we're slighlty uneasy about the apparant fix but will accept it with gratitude as were running out of ideas fast.