There is a MySQL postfix database and all postfix config are generally in /etc/postfix.
Most paths are stored in /etc/postfix/main.cf
edits main.cf and adds "inet_protocols = ipv4"
if you don't have an inet_protocols line in main.cf.
inet_protocols = ipv4
It's a common question that we receive here at Mailgun about SMTP port numbers. To ensure connectivity to our Simple Mail Transfer Protocol (SMTP) endpoint, Mailgun offers multiple SMTP port options, but which one should you use to send email messages? We’ll take a historical look at each SMTP...