PHP Mailing list software..

Can anyone make a recommendation for me? I'm looking to tie mailing lists in to my existing site, which is coded in php/mysql. I would be looking for a script that has browseable archives, ability to restrict access to them to subscribers only, and the ability to send mail to the list a web form, which would require a u/p stored in mysql, preferably in md5 format. I know I'll have to do a lot of customization to get it to integrate into my site, but I'm looking for a solid script that I need to tweak the least. Any suggestions? Thanks, Chad Day