port 25

There are many reasons why you would want to configure Postfix to send email using an external SMTP provider such as Mandrill, SendGrid, Amazon SES, or any other SMTP server. One reason is to avoid getting your mail flagged as spam if your current server’s IP has been added to a spam list. Another very common reason would be being stuck behind port 25 (other ports included with some hosts) – host restricted, it’s becoming ever so common now due to the vulnerable nature of a mail-server being on...