I actually use the script to send our customer mailings, so now it works ;-).
http://pypersomail.sourceforge.net/

Some features:
– sending personalised emails 1 by 1, using CSV file as input
– throttling: the script waits for 60 seconds between batches of 500 mails, otherwise it can bring its SMTP server on its knees
– progress: print a line of logging every 250 messages, so you see what’s happening

TODO:
– automatically generate TXT template from HTML template
– check for email address syntax (e.g. wrong TLD, no ‘@’ sign, …)
– send summary information to source email address when finished
– find some system for processing of bounces
– use a black-list of people never to send anything to