Score:-1

Exchange 2013 MX priority

lt flag

My exchange server 2013 when the destination domain has more than one MX record does not choose the MX record with the highest priority and is always trying to deliver to the lowest priority mx record.

0   cmcantanhede-pt0e.mail.protection.outlook.com   104.47.51.138
Microsoft Corporation (AS8075)  60 min  Blacklist Check      SMTP Test
20  mail.cm-cantanhede.pt   194.65.129.164
Unknown (AS3243)    60 min  Blacklist Check      SMTP Test

In this example, it always tries to deliver to the host with the MX record with priority 20, which is wrong

jp flag
"MX records contain a preference indication that MUST be used in sorting if more than one such record appears (see below). **Lower numbers are more preferred than higher ones.**" [RFC 5321, 5.1](https://www.rfc-editor.org/rfc/rfc5321.html#section-5.1)
Nikita Kipriyanov avatar
za flag
Well, there are records with prio 0 and 20, 0 < 20, however it chooses 20. I thought this was the point of a question?
Score:2
pl flag

By Wikipedia: According to RFC 5321, the lowest-numbered records are the most preferred.

Thus this is a configuration (if which needs to be corrected) on the recipient's end.

However, in Exchange you can use the following method as a workaround:

create an additional send connector for this recipient domain and specify a smart host (the server you would like to deliver messages to)

How to: Create a Send connector to route outbound mail through a smart host

A thread in the similar situation from Spiceworks: Use priority MX records for Receipeint

I sit in a Tesla and translated this thread with Ai:

mangohost

Post an answer

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