Best way to throttle smtp 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 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.

3) Possibly handling this via a scheduled stored procedure

Are any of these the best approach?

Answer 1

1) This feature isn't available without Exchange Server.

2 and 3) It really depends on what you prefer to write software in. Personally I prefer the VS.Net IDE to writing stored procedures.

I was looking around for various mail servers that were cheaper than exchange that supported throttling. hMailServer doesn't, MailEnable doesn't. It looked like IceWarp (/Merak) Mail Server might...you may want to download the trial for that and see if there are any SMTP settings to do that before you write your own. Just the Mail Server component is $312.