Bulk HTML Emails - Way to manage the Emails with subscribe/unsubscribe?

[jarmanje]

Hi there, I have about 500 customer emails in my mysql database and I'd like to start an html email once per month for offers etc

Please could you recommend me a way to put these emails in to some sort of 'subscription' and manage who is on or off the list.

Once they register on my (flash based) website, i could add them somehow to this list as a new subscription.

Are there services or ready-made php/etc based apps I can download?

I'm very new to such a thing. This will not be spam emails, the customers will be expecting such Emails...