ME020467 - TRB: Mail server resides behind a proxy and keeps getting blacklisted because the HELO/EHLO greeting name does not resolve correctly


Remote servers may reject outbound messages and return a bounce message that contains the following error:   

MailEnable: Message could not be delivered to some recipients.
The following recipient(s) could not be reached:

Recipient: [
Reason: Remote SMTP Server Returned: 553 Bogus helo


If MailEnable resides behind an ISP or third party proxy which requires mail to be routed out via the proxy this will effectively change the source sending IP address to be the proxies IP address.  This can potentially result in the message being rejected and possibly the IP address being blacklisted by remote servers when the HELO/EHLO ("default mail domain name") greeting name is exchanged and a lookup on this is performed by the remote server. I f the "default mail domain name" does not resolve back to the IP address of the sending proxy/server, then the remote server may consider the sender as a spammer.  


A DNS "A" record for the "Default mail domain name" will need to be configured so that it points to the IP address of the proxy.


To determine if the "default mail domain name (HELO/EHLO greeting name)" is set correctly, inspection of the received header line of a sent message is required to determine the source IP address. Then you can open a command prompt and use the "ping" or "nslookup" commands to determine the IP address of the "Default mail domain name" and see if it matches the source IP address within the received header line in the message.

Product:MailEnable (All Versions)
Keywords:553 HELO greeting name default mail domain name blacklisted proxy black list
Class:TRB: Troubleshooting (Configuration or Environment)
Revised:Wednesday, May 4, 2016