I'm trying to setup users on a Exchange 2003 SP2 server to access email outside the office using POP. They do not want to use OWA. I added the POP3 protocol on the server and it works fine for receiving emails but when I try to send I get the following error.
An unknown error has occurred. Subject 'TEST', Account: 'TEST', Server: '##.###.##.###', Protocol: SMTP, Server Response: '554 5.7.1 This message has been blocked because the HELO/EHLO domain is invalid', Port: 25, Secure(SSL): No, Server Error: 554, Error Number: 0x800CCC6F
I've tried different settings in Outlook 2003 for authentication but I cannot send any emails through my POP configuration in Outlook.
Internally, email with the Microsoft Exchange server settings works fine.