I have a site with 250k members and I want to send a monthly newsletter to them. I have a in-house coded script to send a newsletter but its without html and I can't manage subscriptions etc...
What software would be best suited for me? I want to be able to sent html mails in a nice custom template and manage subscriptions, and be able to add-on new emails to my list since my site grows daily in around 750 users.
Or would buying a custom script integrated in my website be better?