AOL, Hotmail, Yahoo, and some other ISPs perform a HELO lookup when receiving messages. If the lookup is not successful, they simply reject to deliver the message to the recipient without sending any error message. There are three possible ways to solve this problem.
1. You can select the "Resolved Internet IP" option in the HELO handshaking settings in the Settings/Advanced screen. The program will perform a DNS query to find out which address points to your IP. This option sometimes does not return the correct values if you are behind a router. If that is the case, you can use the http://network-tools.com/
service to check your IP address and look for "Host name" which should then be copied into the "Use this Identification" box in HELO handshaking settings.
2. Try to change the server identity in the HELO handshaking settings in the Settings/Advanced screen to the "mail.domain.com" format. For example, if your ISP provides e-mail address such as firstname.lastname@example.org
, set the HELO handshaking identification to mail.domain.com. Try also with only 'domain.com' format.
3. If you have a domain name that points to your computer's IP address, then enter that domain name in the HELO handshaking settings in PostCast Server. You can use the no-ip.com service to host a domain name on your computer.