Email Bounce back from External sender - Recipients Domain does not exist

[maxrebo]

Bit of a strange one this..

I have an external user attempting to send an email to one of our teaching staff , it keeps bouncing back with the error

 

 

Your message couldn't be delivered. The Domain Name System (DNS) reported that therecipient's domain does not exist

Same external sender can send and receive from me (same domain as teaching staff member)

 

 

The only thing that has changed with this user is we have changed her primary email address to her new surname, previous name still exists as a secondary\Aliasemail address, but external user can't send to that either (receives same bounce back error)

Anyone have any clues where the error lies?

Edited October 18, 2023 by ZeroHour

[StormTrooper59]

I would check by emailing the teaching staff member with a non-school email account such as a gmail for eg, and see if they receive it. If they do then sounds like a mistyped or incorrect email on the external senders part, and perhaps it has cashed the details incorrectly.

[jthompson]

If I were a betting man I'd put money on it being a typo of the domain name.

 

From your address, send a message with both of them as recipients, and ask the external sender to do a reply all as a test.

[bknaggs]

Can you get them to forward the bounce to you so you can see the error?

[chaplic]

I had a similar issue at the start of my career; one chap got NDRs email someone else. I was loosing my marbles as to whats wrong so walked to the desk of the individual in question to check his PC as I was out of Ideas; it was then he confessed he's setup an inbox rule to fake an NDR back to that one user.

 

I'm sure that's not the case here, but could there be a rule forwarding that email somewhere else that no longer exists? Message tracking is your friend.

[dhicks]

If I were a betting man I'd put money on it being a typo of the domain name.

 

I recently spent a couple of hours trying to figure out why an email address was bouncing, carefully checking the domain name without noticing they were using .co.uk, not .com...

[maxrebo]

Yeah, they've forwarded the email to me and the error, ...it lists email of staff member in our school (correct email and domain) and states

 

Your message couldn't be delivered. The Domain Name System (DNS) reported that therecipient's domain does not exist

[maxrebo]

definitely .co.uk over .com, so correct.

 

I've asked them to delete any saved email addresses, and type the full email in again, same bounce back

 

Ive sent a email to this user and they have replied, no problems.

 

Very odd