Send Server SMTP Mail through ISP Email (Spectrum)

This short guide will show you how to send emails on your server through your Internet Service Providers (ISP) email address. This is useful because spamhaus may flag your IP and you will no longer be able to send emails through your server. Using your internet service providers email server will allow you to still send emails without problems.

Remove your IP from the SpamHaus database:
https://check.spamhaus.org/

Bash script (mailtest.sh) to test email server:
https://pastebin.com/UnaV1w2r

Configure your /etc/postfix/relayhost_passwd file:
https://www.dnsexit.com/support/mailrelay/postfix.html

Configure your /etc/postfix/main.cf file:
https://serverfault.com/questions/1042870/getting-postfix-to-relay-smtp-ssl-tls-to-charter-spectrum

Login and find your spectrum email and password:
https://www.spectrum.net/

source

by George Scott

linux smtp server