We are building a custom system for a few clients of ours, and our hosting company doesn’t like that they could send more than 250 in one hour, saying it will be blocked as per the AUP terms. icontact and constant contact won’t work for us, as we need the emails to be sent using our custom php application. What do you all recommend?
MailChimp are good, take a look at [URL=“http://www.campaignmonitor.com/”]Campaign Monitor too.
I’ve used MailChimp in the past and barring a few small annoyances, their supplied php library is very easy to use.
do you have to use their systems, or can you just use their mail servers?
Systems? You essentially, sync your user base with their system and use it to mail specified users.
Your users are completely unaware of the process.
well, what i mean is we need to be able to use our system to generate the dynamic emails. For instance: Hello (user name) click here to goto your page (www.link.com/userid=userid’snumber) does that make sense? Thanks for your help in advance!
Hey, no problem! 
Sure that’s not a problem at all, you may have to jump through a few hoops but it’s possible.