IMail - Error: 550 not local host not a gateway

Question/Problem: I get this error when I try to send email to blah@not-any.com: 550 not local host not-any.com, not a gateway

Answer/Solution: Make sure your mail client is set to do SMTP authentication ("My outgoing mail server requires authentication").

The "Mail Relay Option" that you have selected prevents IMail from sending your message to that address.

In SMTP Security (IMail Administrator | localhost | Services | SMTP | SMTP Security) you want Relay for Addresses. List the IP addresses (and/or subnets) that you want to Relay Mail For.

No Mail Relay is also a secure setting.

Note that it is necessary to stop and restart the SMTP service after the change. You should also stop and restart the Queue Manager service.

Users who send from IP addresses that you do not list must set their mail clients to do an SMTP login ("My outgoing mail server requires authentication").

Please see:
IMail - Mail Relay Options

IMail Server 8.2 User's Guide - Security Strategies

Eudora users, see:

IMail - SMTP login problem for Eudora