I also observed this problem.
The e-mail gets stuck in Postfix’s mail queue and it will just stay there until the DKIM is disabled.
Do you guys see any errors in your mail logs while those messages are sitting in the Postfix queue?
Also, the way DKIM functions was reworked a bit changed in Virtualmin 3.82 – which should hopefully have fixed some issues. Were your DKIM settings generated with the most recent version of Virtualmin?
-Eric
I have not checked the mail log, I doubt I would know what to look for, and yes, this is happening on version 3.82
Anyone who is planning on setting up DKIM on Debian or Ubuntu should hold off until the 3.82-2 release of Virtualmin comes out, as I just discovered a bug that can cause the deleting of the /etc/default directory. Or you can enter something other than default for the selector name … I recommend the current year, like 2010