Comment 6 for bug 1756009

Oh, I didn't expect that version 2 was still alive. I'm sorry about my mistake.

Thank you very much for help and the hint to the commands.

With the help of the commands, I was able to determine that quite a few users were actually disabled, although this was not clear from the settings. Probably the users were disabled after several emails could not be delivered to them.
After I explicitly enabled them in the interface, they are no longer disabled according to the commands. I hope now that all problems are solved with that.