DigitalOcean DigitalOcean SMTP Outbound Email Blocked By Default

Heads up that DigitalOcean now disables SMTP email outbound sending on new Droplet VPS servers by default to combat spam. Other VPS providers may also block SMTP outbound emails due to spam too. So you'd have to use a 3rd party SMTP provider for outbound emails from the server. I use Amazon SES and PepiPost/NetcoreCloud right now which seem to hide/remove the real server's IP address from mail headers. Other SMTP providers mentioned below may not hide/remove the real server's IP address and thus leak your real server's IP even when you use Cloudflare in front of your server.

Centmin Mod is provided as is so no official support for reconfiguring Postfix MTA mail server beyond what Centmin Mod initial setups up and configures for Postfix local outbound email sending.

However, if you want to sent email outbound via remote mail server like with smtp email providers like Amazon SES, PepiPost/NetcoreCloud, Mailgun, Mailjet etc there are various online guides if you search for "centos postfix relay". Instructions for Debian and Ubuntu may differ from CentOS 6 or CentOS 7 operating systems that Centmin Mod runs on so bear that in mind and read many online guides to understand the best gist of configuring Postfix relay for external mail sending via remote smtp server.

Remember, troubleshooting and setup is all on you as I provide no support, however fellow forum members are welcome to help each other out.

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The following guides are a start and you should read them all and re-read them to get an understanding of what is required paying attention to differences of CentOS 6 vs CentoS 7 vs Debian/Ubuntu if any.

Note you can skip installing Postfix via yum as it's already installed

• Configure Postfix to use Gmail as a Mail Relay
• Integrating Amazon SES with Postfix - Amazon Simple Email Service (leave off the sudo in the commands used as Centmin Mod uses full root user and not sudo user)
• Integrating Postfix with Dyn’s Email Delivery
• Postfix - Mailjet Code Sample - Mailjet & Overview
• PepiPost/NetcoreCloud Postfix Relay

You can also set up a test VPS with an hourly billing provider and test various Postfix relay guides until you find one that works for you etc.

 

Also updated official Centmin Mod Getting Started Guide for step 20 with this info too.