I am running a Xenforo forum on a VPS and due to GoDaddy's sucky mail method I switched to using an external mail handler called Pepipost. Works great except for any email that is generated by the forum that goes back to an email on the website (such as a user/visitor filling out a Contact Us form, or a user sending a message or generating an email that goes to an account with an email address that = the forum URL like webmaster@***.com), that email bounces like this
and pepipost is telling me thisReporting-MTA: dns;****.****.com
Received-From-MTA: dns;****.*****.com (ip address hidden)
Arrival-Date: Fri, 12 Aug 2016 07:16:27 +0530
Status: 5.0.0 (undefined status)
Remote-MTA: dns;****.org (ip address hidden)
Diagnostic-Code: smtp;550 Verification failed for <*****-*****-0-*******.org@delivery.*****.org> No Such User Here Sender verify failed
I managed to ssh into the server and sudo su - to the root and look at the exim config but I have no clue what I am looking for and don't see what they are talking about.It seems that you are using EXIM as MTA at your end. Exim has a feature to VERIFY if the SENDER has a valid mailbox before accepting the email from that sender. During verification, if the connection fails, mail is not accepted and the error you mentioned is thrown.
The solution for this is ,the exim config contains entries like this:
deny message = Sender verify failed
!verify = sender
This should be disabled.
I run this same exact setup on another forum that is on a shared host and have zero issues...
Any help would be appreciated. Remember, newbie.