[linuxthefish]

You should look into a mail sending service such as http://mailchimp.com, I've used them successfully before.

Most server hosts won't like you sending lots of email at once, as it might get their IP blacklisted!

https://www.digitalocean.com/tos

Quote:

2.4 In addition to being forbidden from performing any acts made illegal by the CAN-SPAM Act, Users may not send bulk email utilizing their Network resources unless they maintain a double-authorized list of subscribed members including IP addresses and relevant contact information, along with following guidelines for including removal links with all sent emails according to the CAN-SPAM act. Users are forbidden from taking any action that would result in their IP addresses, or any IP address associated with DigitalOcean or other Users, being placed on the Spamhaus.org blacklist.