Posts: 1
Registered: ‎31-10-2018

Email and domain problems , Error 550 5.1.10

Have been in touch with the support team, waited several times for changes to take effect after 48 hours, but still no joy.


It's been a month now!!!

Tickets 1-104039494 , 1-104032868


Having ongoing problems with email for a domain, let's call it, that I transferred in to BT a month ago.

There was already an existing domain,


I don't think the mailboxes have been activated/set up correctly...

... The backend of BT Business Email Lite package is managed by them through an Exchange setup?



Emails to any of 3 specified addresses bounce back to sender as underliverable with error

550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient [] not found by SMTP address lookup

and when trying to log in to emails through the office 365 portal at

I get

"Your account or password is incorrect." or "Unknown user"


Settings folllow...:


Manage Services, Manage Email Accounts

Business Email Lite

The mailbox for COMPANYA (primary user) is Active (no problems with emails for this domain)

The 3 mailboxes for COMPANYB are (now) listed as Active


Here are the zone configurations in
CNAME mail
A *
A *
CNAME autodiscover
TXT @ MS=ms00000000 (EDITED)
MX @ 1     <------
TXT @ v=spf1 -all


The MX record for working COMPANYA looks different?
<------ MX @ 10





Super User
Posts: 70
Registered: ‎29-05-2018

Re: Email and domain problems , Error 550 5.1.10

Hey gazj,


You're best speaking with the support team again to let them know that you've waited 48 hours with no solution. Do the mailboxes appear to be registered on the BT Business portal and are you able to log in with those mailboxes using this website? If so, it sounds like an issue with the mail server and the second line team can check if the mailboxes have been configured correctly via their Office 365 tenant access. 


Thanks, Bobby

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