I work for a small company and we have fallen into the fad of "email campaigns" a.k.a junk mail. So far the company has gotten a subscriber list from our website, and paid a good chunk of change for a emailer program. The problem is, Our list has close to 4,000 people on it and growing. with Gmail only allowing 100 emails per account through on SMTP and I am on a tight budget so I can't hire anyone else.
I was thinking of doing a dedicated mail server off of the website server we have running in the office. Is it possible to make emails on your own server, and then send it through your own SMTP? If it is, what software would I need? Preferably free or low cost at least. We run a WAMP server, I set it up just for information, but I could switch it to LAMP or whatever if need be.