I Want To Be A Whitehead! If you want to be “one of the good guys” and follow the rules by which spam is sorted out from other mail servers, you should follow some of these guidelines:
(Note that some basic knowledge isn't covered here; You should know what an MX record is)
- You shouldn't try to send email directly from dynamic IP address ranges (such as dialup pools). You will exprience problems with various ISP's blocking port 25, and RBL's listing you from the start.
- If you want to send mail from a dialup account, authorize to an external mail server and relay through it. Common ways to do this are to use TLS, SMTP after POP, or Authenticated SMTP. Very modern ways involve server certificates.
- If you are on a static IP address on the Internet, you should make sure your DNS and Citadel Settings match the following criteria:
- You should configure Administration → General → Fully qualified domain name to lets say “mail.yournode.org”
- Find out from which IP address your outbound connections originate. You need two machines for that. Connect from your Citadel server to some service on the other box, and look at netstat -an If will show your IP address, for example 18.104.22.168
- Make sure this IP is resolvable via Reverse DNS to the correct name (such as mail.yournode.org). The command will be something like host 22.214.171.124. Usually this is configured at your ISP's DNS server. To locate the responsible party for this configuration, you can do (for example) whois 126.96.36.199
- Make sure that your host is one of the listed MX records for your domain. For example, “mail.yournode.org” should be listed if you run a command like host -t mx yournode.org
- Of course, you should also make sure your forward DNS lookup works properly, with a command like host mail.yournode.org, it should be 188.8.131.52