[Dovecot] Performing an action on mail receipt

[Andrew Beverley]

Dear all,

I would like to perform an action for certain users each time a mail
arrives via LMTP. I would like to send an email notification to an
external email address when new mail has arrived for certain users
(note: not a forward).

I am assuming that creating my own plugin using the existing "notify"
plugin is the way to go. However, before I go down that route, I'd like
to check that is the best approach? Or would it be better to perform
this sort of thing before the mail reaches Dovecot?

Assuming writing a plugin is answer, do they have to be written in C?

Dovecot version: 2.1.7

Thanks,

Andy