Best way to throttle email on Windows Server 2008

Question

I have a server with SMTP set up for my site's outbound email. In order to not get blacklisted I'd like to limit outbound emails to under an arbitrary threshold (let's say 500 per hour). What's the best way to implement this?

The two possibilities I see would be:

1) Some sort of outbound throttling within the SMTP Virtual Server (Not sure if this is possible when not on a full fledged Exchange Server)

2) Create a windows service that polls a database table for emails, processes the TOP N results and then sleeps for X Minutes.

Are either of these the best approach?

Answer 1

Just write a stored procedure to process the top N results and schedule the stored procedure to run at frequent intervals.