finding out that a message was delivered to a mailbox

[Boylan, Ross]

When a message is delivered to a mail folder I would like an external (but on the same machine) program to know about it.

This seems like a job for the SIEVE enotify extension https://tools.ietf.org/html/rfc5435 but I would like to use Debian stable, which is cyrus 2.4.  I think the extension was added in 2.5.  Second, even if I use 2.5, I don't know what specific notification mechanisms cyrus supports.

I could just stick with my original plan of having a program monitor the cyrus logs for info on message delivery--all I need is the message identifier and the folder it was delivered to.

Some messages are likely to be pre-sorted, with the folder already specified when cyrus gets the message.  But I assume they all  go through sieve.

Any suggestions, particularly about how to do what I want in 2.4?

Thanks.
Ross Boylan