O365 cant find email recipient

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xpd

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#233860 7-May-2018 10:02

Fun times with email, but suspect its just Office365 having issues....

Domain A (hosted with O365)is trying to send email to Domain B (hosted elsewhere). has previously worked fine.

Domain A sends email to Domain B but gets response straight away from O365 that the email address dosent exist.

Sent email from Gmail to Domain B, email arrives fine.

Any ideas what could be causing this ?

XPD / Gavin

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dfnt

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#2009057 7-May-2018 10:12

Have you got domain B present as a domain within domain A's tenant?

Any connectors for domain B forwarding to a non existent relay etc

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#2009061 7-May-2018 10:15

Just beaten to this suggestion.

Either something is cached badly and should drop off on its own or Office365 thinks it has control of the domain and is rejecting because of that. The rejection notice should have the name of the server telling you to sod off?

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xpd

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#2009117 7-May-2018 12:01

Error Details

Reported error: 550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient (emailaddress) not found by SMTP address lookup
DSN generated by: MEAPR01MB2981.ausprd01.prod.outlook.com

Message Hops
TO WITH RELAY TIME
MEAPR01MB2807.ausprd01.prod.outlook.com mapi 1 sec
MEAPR01MB2981.ausprd01.prod.outlook.com Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) *

XPD / Gavin

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dfnt

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#2009122 7-May-2018 12:10

Has domain B setup as a new O365 tenant, but the MX records are still pointing to <whatever>?

If so, I believe the nature of O365 is that it'll try send internally, and if the domain is authoritative in O365 it won't go out

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xpd

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#2009184 7-May-2018 13:06

nas:

Has domain B setup as a new O365 tenant, but the MX records are still pointing to <whatever>?

If so, I believe the nature of O365 is that it'll try send internally, and if the domain is authoritative in O365 it won't go out

Domain B has never been part of O365, its run out of my garage server and always has been :)

Its just weird its only started doing this over the last few days, and noones made any changes to anything (I hold all the account access).

XPD / Gavin

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#2009223 7-May-2018 14:05

That is weird indeed, feel free to PM me the email and I can test from my O365'd domain

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#2009586 7-May-2018 20:36

Looks suspiciously like somehow <domain B> has gotten itself loaded somewhere in the office 365 system.

(Otherwise I would have expected comms errors to indicate a machine other than O365 to respond, or for you to get a NXDomain type of response).

The other thing it *could* be is your garage server blocking office365?

If you try checking the message flow (within Exchange admin in Office 365) that might aid in getting there (Assuming you have access to that portion of office 365)

Might be worth opening a ticket with office365 and getting them to check as well?

If you need other set of eyes testing, just PM me.

Cheers!

dfnt

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#2009592 7-May-2018 20:50

I sent an email from my O365 email and he received it fine, so hopefully that'll help him narrow it down a bit

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xpd

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#2015762 14-May-2018 14:19

Right, turns out you were all pretty much bang on the money ;)

Ended up contacting MS support who advised that the domain B was loaded into Domain A's system. I found where and have started the process of removing it, so hopefully tonight all is well ;)

Appears the owner of the domain, has given the admin account to someone else who then went and had a play at adding Domain B into Domain A's account somehow.... and fudged it up. But of course noone will own up to it :-p

The owner has now lost his admin rights and everything will be run through me. (As it was meant to be anyway).

So thanks all for your input :)

XPD / Gavin

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