Email Delivery Issues between cPanel and Microsoft Servers

Roberto Cholaky

• December 16, 2023 00:39

I have a cPanel server hosting a website "site1.com," which uses cPanel as its mail server. Additionally, there is another website, "site2.com," which manages its DNS on Cloudflare and has its mail server with Microsoft.

When attempting to send an email from the cPanel mail server ('site1.com') to a user with an email from the "site2.com" domain, which has its mail server on Microsoft, I encounter the following message: Server Error: '550 No Such User Here.'

When trying to send an email from the Microsoft mail server with the domain "site2.com" to a user with an email from the "site1.com" domain, the following error message appears: "550 5.7.363 Remote server returned sender verification failed -> 550 Verification failed for <user@site2.com>; No Such User Here; Sender verify failed."

I have attempted to modify the DNS settings on both cPanel and Cloudflare, but I have not been able to resolve the issue. Please help.

• 

  rbairwell

  • December 16, 2023 01:54

  The "No such user" error is one produced by the receiving server and it would therefore indicate the email is reaching the destination but there is no user matching that email address there - the "local part" (before the @ is probably mis-spelt).

  Of course, assuming you've checked that simple issue:

  1) Using tools such as https://mxtoolbox.com/diagnostic.aspx , I assume both domain names have valid hostnames and reverse DNS - and that when you use site1.com (cPanel) it provides your server's IP address and hostname.

  2) You are able to send to both email addresses from a third party service okay.

  3) In WHM under Email->"Mail Troubleshooter" , when you enter the site1.com email address, do you get a BLUE box with "virtual_user to local delivery"?

  4) In WHM under Email->"Mail Troubleshooter" , when you enter the site2.com email address,do you get multiple GREEN fields fields saying something like "dkim_lookup via site2.com.olc.protection.outlook.com [52...] MX=10.." ?

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• 

  Damian

  • December 16, 2023 11:18

  Is there a dns zone for site2.com on the same server or dns cluster as site1.com?

  I'm thinking there may be. If the website for site2 is hosted locally then the dns locally needs to point the Microsoft for mail, email routing set to remote, and no mx entires potting to the local server.

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