Last year around this time, we ran a promotion. We let anyone and everyone register an account for DD, and play for free during the week of GDC. This was pretty cool, got us some nice exposure, and made us some sales … it also completely killed the e-mail service on our host for two whole days. We managed to write a mail queue system that would send out 100 e-mails per hour (the limit set by our webhost), but before we got that running, mails were getting lost left and right.
We’ve spoken to our webhost about raising the limit, but they don’t seem to understand that we send out mail ‘on request’ not in mailing lists, but we still need it to be automated. Searching around the internet for a bit turned up Madrill, an offshoot of MailChimp. Mailhimp does newsletter stuff, and they extended the business to do transactional mail. Madrill is nice in that it has an hourly limit, but that limit gets shifted up as your needs increase and as your reputation becomes better (no spam, no bounces, etc).
Switching over to Mandrill means we can open the tap on our side of the mail process a little more, letting through 100 emails every 10 minutes instead of 15 every 10 minutes. Once we have some more time on our hands, we’ll switch our mail sends to direct through Mandrill immediately, instead of sitting in our queue. What this should mean for you is faster e-mails for password changes, and faster replies when buying copies of the game. Also fast e-mails when next we do a “free for a while” promotion …