This tutorial is going to show you how to set up Postfix SMTP relay with Mailjet. Postfix is a popular open-source SMTP server. Previously I wrote an article how to easily set up a full-blown email server on Ubuntu with iRedMail, which helped a lot of readers run their own email server.
However, some readers told me that port 25 is blocked by hosting provider or ISP, so they couldn’t send email. I run my email server on Linode, which by default does not block port 25. I also know that Vultr by default blocks port 25, but they would unblock it if you ask them to. Some other hosting providers or ISPs like DigitalOcean would not unblock port 25.
Read full tutorial here: https://www.linuxbabe.com/mail-server/postfix-smtp-relay
