I hope this isn't too OT for this list, but here goes:

I've just copied and hacked the SentOutDB plugin and its associated rule
to make a plugin for a private whitelist. The plugin queries a view of
my PostgreSQL-based mail archive. This whitelists anybody that mail has
been sent to.

The plugin and whitelisting are working reliably but writing the plugin
reminded me that my knowledge of Perl is out of date. I learnt it in the
latter days of Perl 4, i.e. before the OO extensions, and haven't used
it since. I learnt from the O'Reilly Camel book, Programming Perl, which
I still have and like.

Now I need a refresher, so if anybody can recommend a suitable book I'd
be grateful. Would the latest edition of Programming Perl be a good