Is there a bug in Forum registration?

Is there a bug?
Someone emailed me wishing to register on my Nabble-based forum.
They said they were still waiting for the email (which one assumes would arrive automatically within a matter of seconds).  AFAIK they had checked their spam.
I tried to replicate the symptoms by logging out of my account and pretending to be a new user attempting to register.  I entered suitable details, and got an on-screen response, "An email has been sent to you".
As with the new applicant, I am still awaiting that automated email.
Is the system currently faulty?

I look forward to your response .
Thanks.
Regards
Paul W
(Webmaster, mymorbic.uk)