Question : email relay problem because ISP limits the number of emails sent per hour

Every now and then I need to send out about 500-1000 emails to our customers. We do this from a mail merge from our database so that all emails are customized.

The problem is that our ISP limits the number of emails sent per hour (only 100 emails per hour).

We have a postfix relay setup so that all emails are sent to this relay server and then relayed to the ISP. So I have 2 options to fix this problem:

1. get another ISP that doesnt limit the number of emails sent per hour (Can I get a  recommendation?)

2. Setup our postfix relay server so that it will "hold" all the emails that we ask it to relay, but release it at a set rate (i.e, 100 emails per hour per account) to adhere to the ISPs policy.
Can someone please help me on how to go about doing this?

For the postfix relay server, we're using ubuntu.

Thank You

Answer : email relay problem because ISP limits the number of emails sent per hour

I'm no postfix expert, but here's what I found:
http://www.irbs.net/internet/postfix/0809/0160.html

I assume (being careful here!) that if you are allowed to send 100 mails per hour, you could set the parameter "default_destination_rate_delay" to 36, to make sure there's a gap of 36 seconds in between mails.

And for what it's worth:
http://policyd.sourceforge.net/readme.html