Why is SMTP blocked?

SMTP port 25 is blocked on all Droplets for new accounts to prevent spam and other abuses of our platform.

Dedicated email deliverability platforms are better at handling deliverability factors like IP reputation. To send mail from DigitalOcean, we recommend using SendGrid:

SendGrid delivers your transactional and marketing emails through the world’s largest cloud-based email delivery platform.
marketplace.digitalocean.com

Even on older accounts where SMTP may be available, we strongly recommend against running your own mail server in favor of using a dedicated email deliverability platform.

Droplets do not have a dedicated IP address.
Configure your firewall to allow outgoing traffic through ports 80 and 443.
There are a few ways to install an SSL on your Droplet, depending on where you get the certificate from.