SMTP server addon for ReadyNAS Ultra?

Hi all,

I have searched a bit but not found any suitable threads and my question is fairly straightforward:
Is there an SMTP server addon for the ReadyNAS Ultra (4)?

I would like a single place to point all of my clients and devices locally in order to send mail, and thus only 1 place to edit the public SMTP settings if I change ISP or mail provider.
The alerts from the ReadyNAS work just fine, but 2 webcams seem to have a problem using the same SMTP server settings when it comes to sending alert mails so I want to try using a local relay instead.

Ideally there would be an addon with a simple interface or config file to specify:
- the listening port
- whether TLS needs to be enabled or not
- the next hop server
- the credentials to use for the next hop server

I am not looking for a full-blown mail server, just a simple SMTP relay (not reachable from the Internet).

Any advice greatly appreciated!

Cheers,
Mr Snrub