How exactly does e-mail marketing work. If you want to send 250 e-mails out to ppl that have bought things from an e-commerce site - how would you go about doing it?
Since you mentioned that you are wondering about this for an e-commerce site, you should check to see if the e-commerce platform you are using has a mailing system built in. It may allow you to send an email, from your server, out to all your customers if they have to submit their email at the time of purchase or when creating an account. It may even allow you to specify which customers are to receive it based on conditions such as physical address, purchase amount, product(s) purchased, etc. If you are looking for an external system... You should read up on autoresponders. You should check to see if you have one available through your website's hosting company (I believe cPanel has one) and an easily applied opt-in signup form. You can also get a full package from some companies where they give you an easy-to-implement signup form along with an autoresponder to simplify your opt-in mailing list situation.