Mail flow issue with multiple MX record

%3CLINGO-SUB%20id%3D%22lingo-sub-2415894%22%20slang%3D%22en-US%22%3EMail%20flow%20issue%20with%20multiple%20MX%20record%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-2415894%22%20slang%3D%22en-US%22%3E%3CP%3EHi%20all%2C%3C%2FP%3E%3CP%3EI'm%20going%20to%20move%20all%20mailboxes%20from%20Mdeamon%20to%20EXO.%20And%20have%20a%20little%20issue%20mail%20flow%20with%20multiple%20MX%20record.%20I%20was%20create%20a%20second%20MX%20record%20point%20to%20EXO%20with%20%3CSTRONG%3Epreference%20%3D%2020%3C%2FSTRONG%3E.%20For%20the%20first%20one%20is%20pointing%20to%20Mdaemon%20with%20%3CSTRONG%3Epreference%20%3D10%3C%2FSTRONG%3E.%3C%2FP%3E%3CP%3E%3CSPAN%20class%3D%22lia-inline-image-display-wrapper%20lia-image-align-inline%22%20image-alt%3D%22MX.png%22%20style%3D%22width%3A%20402px%3B%22%3E%3CIMG%20src%3D%22https%3A%2F%2Ftechcommunity.microsoft.com%2Ft5%2Fimage%2Fserverpage%2Fimage-id%2F286266iE0B36347843B493A%2Fimage-size%2Flarge%3Fv%3Dv2%26amp%3Bpx%3D999%22%20role%3D%22button%22%20title%3D%22MX.png%22%20alt%3D%22MX.png%22%20%2F%3E%3C%2FSPAN%3E%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EAfter%20i%20created%20the%20second%20MX%20record%2C%20Some%20people%20(my%20partner)%20they%20already%20using%20EXO%20to%20sending%20email%20to%20me%20got%20failed%20with%20message%20%22%20The%20recipients%20not%20found..%20%22%20like%20a%20picture%20below%3C%2FP%3E%3CP%3E%3CSPAN%20class%3D%22lia-inline-image-display-wrapper%20lia-image-align-inline%22%20image-alt%3D%22failed.png%22%20style%3D%22width%3A%20812px%3B%22%3E%3CIMG%20src%3D%22https%3A%2F%2Ftechcommunity.microsoft.com%2Ft5%2Fimage%2Fserverpage%2Fimage-id%2F286267iF504A0825EF9CD04%2Fimage-size%2Flarge%3Fv%3Dv2%26amp%3Bpx%3D999%22%20role%3D%22button%22%20title%3D%22failed.png%22%20alt%3D%22failed.png%22%20%2F%3E%3C%2FSPAN%3E%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3ESo%20i%20check%20around%20and%20founded%20the%20email%20routed%20by%20the%20second%20MX%20record%20point%20to%20EXO%20despite%20the%20first%20one%20is%20the%20primary.%20This%20issue%20just%20happed%20with%20sender%20who%20using%20EXO%20service%20and%20send%20an%20email%20to%20me.%20Another%20sender%20is%20normal%2C%20email%20routed%20by%20the%20primary%20MX%20record%20point%20to%20Mdaemon.%3C%2FP%3E%3CP%3EAfter%20that%20i%20was%20deleted%20the%20second%20MX%20record%20and%20the%20mail%20flow%20be%20normal%20again.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3E%3CSTRONG%3EThe%20question%20is%3C%2FSTRONG%3E%3A%20W%3CU%3Ehen%20i%20created%2002%20MX%20record%20with%20the%20second%20record%20pointing%20to%20EXO.%20And%20the%20email%20is%20sending%20by%20sender%20who%20is%20using%20EXO%20service.%20It's%20looking%20the%20mx%20route%20to%20the%20same%20platform%20(EXO)%20first%20then%20the%20primary%20MX%20record%20%3F%3C%2FU%3E%26nbsp%3B%20-%3CSTRONG%3E%26gt%3B%26nbsp%3Bif%20my%20hypothesis%20is%20true.%20Please%20confirm%20for%20me%20and%20provide%20me%20a%20docs%20for%20it%3C%2FSTRONG%3E%3C%2FP%3E%3CP%3E%3CSTRONG%3EIf%20my%20point%20is%20wrong%20please%20correct%20for%20me%3C%2FSTRONG%3E.%20Tks%20all%3C%2FP%3E%3C%2FLINGO-BODY%3E%3CLINGO-LABS%20id%3D%22lingo-labs-2415894%22%20slang%3D%22en-US%22%3E%3CLINGO-LABEL%3EExchange%20Online%3C%2FLINGO-LABEL%3E%3C%2FLINGO-LABS%3E
New Contributor

Hi all,

I'm going to move all mailboxes from Mdeamon to EXO. And have a little issue mail flow with multiple MX record. I was create a second MX record point to EXO with preference = 20. For the first one is pointing to Mdaemon with preference =10.

MX.png

 

After i created the second MX record, Some people (my partner) they already using EXO to sending email to me got failed with message " The recipients not found.. " like a picture below

failed.png

 

So i check around and founded the email routed by the second MX record point to EXO despite the first one is the primary. This issue just happed with sender who using EXO service and send an email to me. Another sender is normal, email routed by the primary MX record point to Mdaemon.

After that i was deleted the second MX record and the mail flow be normal again.

 

The question is: When i created 02 MX record with the second record pointing to EXO. And the email is sending by sender who is using EXO service. It's looking the mx route to the same platform (EXO) first then the primary MX record ?  -> if my hypothesis is true. Please confirm for me and provide me a docs for it

If my point is wrong please correct for me. Tks all

1 Reply
This shouldn't be the case, but regardless if you can reproduce it, best contact support.