Which web Based Email/Mail server?

[jarekn]

Hello!

Ok, my site is going through major changes as we speak... few hacks, custom pages, new graphics etc....

One thing I'd like to add is Free Web Based Email....

I am running W2K and will need to install new Mail server and what not...

My site currently has 8000 members, but my mailing list has over 150'000... I hope to get most of those users on to the new system... on top of that I've got few other things happening which I hope will boost the membership to 500'000 members with in the next 6 months....

For now I'll run the forum and mail server on the same box... but will move the mail to another dedicated box as soon as required... mind you with 500'000 members the hardware requirements will be nuts...just hard drive space will proably need 4TB - I found a server... but it's crazy money! http://www.tigerdirect.ca/applicatio...095&CatId=1208

So for now it's out of question....

My question is this... Which mail server (software) to use? I'll need one that will be capable of handling 500'000+ users and that will some how easily integrate with vBulletin... each user in forum should have email account... any time they check their email it should be running of the mail server ... I saw some integrations where the emails would be imported in to the vBulletin DB but that is not an option for me... I want the two to run on different servers for obvious reasons...

The mail server will also have to allow me to add header/footer to all outgoing messages... for banners etc...

Your help would be very much apreciated


Please let me know what you think....