I have some issues with the email.
I have a bit unorthodox mail setup.
We use Microsoft Exhange for all of out emails but we are also using KeyHelp email server for some of our automated systems, but only to send, not to recieve emails.
The issue is that when sending email from keyhelp to our exchange we are getting Recipient address rejected: User unknown in virtual mailbox table error.
I assume that is because keyhelp email server says "Hey that domain is hosted on me, i just locally deliver the email instead of sending it out" but that post box does not exist on the keyhelp server only on the Microsoft exhange server.
Example. Sending email from email@example.com (on keyhelp) to firstname.lastname@example.org (on exhange), will give that error. If I send from email@example.com (on keyhelp) to firstname.lastname@example.org (also on keyhelp) the email gets delivered to the postbox on keyhelp. So it strenghtens my beliefs that the mail server just figures that the domain is hosted on the keyhelp server and tries to deliver it locally.
How can I fix it so that all emails going out of keyhelp is sent out regardless if the domain is hosted on the same server? We only use keyhelp as SMTP server, no emails are being delivered as we use exhange for most of our emails.
There is a option like: disable internal DNS for this domain
Check the box and it should work.
I don‘t know the exact spelling of the option because i use the german translation.
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Thank you for your response. The DNS is disabled for that domain on KeyHelp. However I cant find anything about internal DNS.