I have been puzzled for a while now. There have been a couple of emails sent from my company and we have been haveing issues getting them delivered.
In one occasion me and and a second employee emailed two other seperate employees in a company. We got back each the following reply from our Exchange server:
Delivery has failed to these recipients or groups:
The server has tried to deliver this message, without success, and has stopped trying. Please try sending this message again. If the problem continues, contact your helpdesk.
On a second occasion another employee tried emailing another individual in a separate company but he did not receive a undelivered reply. He received no information but the email was not delivered. Also, on our log it shows that it was delivered.
I know they are two different occasions and outcomes but I ran a address verification on the web for all 3 emails and I am told server doesn't allow email address verification. Can this be the reason why they are not delivered? When sending the email from a Gmail it works but from our Exchange it does not. Is there a setting that doesn't allow Exchange to deliver to email address that are not verified?
Please let me know if anyone of you dealt with this before.
This could be related to you not having a PTR record setup & the FQDN on the send connector.
Typically your ISP will create this record or if you manage your external DNS you can set this up.
I guess restarting the transport services and rebooting can help you to resolve the issue.
I have found the same problem discussed over some forums.
Here I am sharing few of them,see if the below thread helpsyou:
Not receiving emails
Outgoing email not delivering - Email and calendar - Office 365 - Microsoft Office 365 Community
Thanks to all you guys. The issue turned out to be out of my hands. It seems that there was a routing problem between Lichtenstein (where our Exchange server is located) and the USA. After discussing the issue with Telecom in Liechtenstein they rerouted to bypass one of their providers and that did the trick. We are now able to send and receive emails to those addresses. :D