What you’re seeing
- People emailing your new domain get a bounce such as 550 5.7.54 unable to relay recipient in non-accepted domain.
- Exchange rejects attempts to give mailboxes an address in the new domain.
- Staff still show only the old domain in their addresses after a rebrand or acquisition.
- Mail for the new domain reaches the server and then goes nowhere, or loops back as undeliverable.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The domain is registered and its MX record points at your server, but Exchange has never been told it is responsible for that domain.
- The domain was defined with the wrong type, for example as a relay domain when Exchange should own it, or the other way around.
- No email address policy includes the new domain, so mailboxes never receive an address in it.
- In a hybrid setup, the domain was added in Microsoft 365 but not on-premises, or only on-premises.
- The spam filter or mail gateway in front of Exchange does not yet accept mail for the new domain.
Why it matters
A new domain usually comes with a business event: a rebrand, a merger, a new product line or a new office. If Exchange does not accept it, customers and partners writing to the new addresses printed on cards, websites and invoices get bounces, which looks unprofessional at exactly the moment you want to make a good impression. Getting the domain type or address policy wrong can also change existing users' reply addresses unexpectedly or open the server to relaying mail it shouldn't.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Will adding a new domain change everyone's current email address?
Not unless you want it to. A new domain can be added as an extra address while everyone keeps their current reply address. We agree which address should be primary before anything changes.
Is there anything else to update besides Exchange?
Often yes: DNS records, any mail filtering service, and sometimes the server certificate if users will connect using the new domain name. Our engineer reviews the whole path so mail flows end to end.