High volume e-mailer

Hi! I'm to design a system for mailing targeted and personalized information to our customers and have a few questions on this. This is what I have to work with: Database server; Oracle Dynamic Reasoning Engine; Autonomy - www.autonomy.com Operating System; Solaris, Linux or BSD MTA: qmail (but open for other suggestions) This is what I need to do: Select e-mail addresses and customer id:s from the Oracle server. Feed the customer id to the Dynamic Reasoning Engine and fetch some personalized information from that based upon profiling. Take this information and parse it into a template with static content. Send the e-mail using MIME-encoding if the customer has signed up for this or plain text if he/she has not. The problem is that I need to be able to send appx. 300.000 such e-mails in a reasonable amount of time and also be able to deal with bounced e-mails in a proper manner. I.e. not just sending them to /dev/null/ but actually removing the bad e-mail addresses from the database when appropriate. I have used qmail and ezmlm for this task before but with that solution I can't tailor each message with personalized content so I figured I'd rewrite the entire system using PHP. My questions are mostly concerning the scalability issues. Do any of you know of a good way to feed some 300K e-mails to the MTA without having it choke from the load? Should I perhaps do a round-robin kind of thing where I send all e-mails that are addresses to an e-mail address starting with a-f to MTA1, g-l to MTA2 and so forth? Better ideas? Also; do anyone of you have any thoughts on bounce handling and how to add this? Do you know of any good PHP e-mail classes out there for sending MIME e-mails? Thanks!! - Nicklas