Queueing email instead of firing immediately

[Pho Tek]

Is there any opensource servlet component that will queue emails rather than sending it immediately ? Most of the javamail wrappers I know - connect to a SMTP server i.e. a socket is opened. What I would like to do is to be able to drop my emails in some outbox directory and a email daemon will wake up and send all emails in the OUTBOX out.
Pho