When @Bmueller sent out a mass message upon reviewing lots of the pages her sig was red linked.
It appears this was due to never having visited these wikis before and thus no local user had been created?
MassMessage should ensure the local user exists in these cases to avoid this undesired behaviour by the combination of extensions.
We have run a script to log @Bmueller into all of the sites & purge the pages on this occasion.