[TYPO3] sr_feuserregister not sending e-mails

[Lewis Jones]

I am running Typo3 4.0.1 and sr_feuserregister 2.5.0.

I have been using this combination now for at least a year and things
have worked fine.

A few days ago I discovered that I was no longer receiving any e-mails
from my website (via sr_feuserregister).

I am not using administrative review of registrations, but am using the
e-mail confirmation system, so that both frontend user and administrator
receive two e-mails in the registration process, first about
confirmation and second about finalising the registration.

Now I receive none.  I get no errors anywhere, just nothing at all.

My e-mail addresses are working, but nothing is coming from
Typo3/sr_feuserregister.

Is there a switch I've reset somewhere?  Is it a templating problem?
Have I trashed the mail server?

Any thoughts would be much appreciated.

Cheers,
Lewis