How MX Record Preference works

[Arie --]

Hi,

How does the MX record preference work?

Lets say, for example, we have 3 MX record for domain @example.com. Assume that the hostnames below are mail server directly.

Pref    Hostname                          IP Address

5        mail-1.example.com          100.100.100.10

10      mail-2.example.com          100.100.100.20

15      mail-3.example.com          100.100.100.30

If a sender wants to send email to user1@example.com and the mail-1.example.com doesn't have account user1@example.com, but the mail-2.example.com have the account for user1@example.com, will the email sending fail? Or will the message send to the mail-2.example.com after mail-1.example.com told that it doesn't have for such user?

Thank you

[balaji.bandi]

As per MX records concern Low Preference is preffered. as per your configuration if pref 5 mail server not available it will try preference 10 MX records.

If you like to Load-Balance with MX records you need to try all same preference. (5 or 10 )

[Arie --]

Hi,
Does it mean that if pref 5 mail server doesn't have the user1@example.com, it will try pref 10 mail server even the pref 5 mail server service is still active?

Thanks

[Ken Stieers · Accepted solution]

Mx records dont work like that.

MX preference is only used at the connection level... can I connect to the ip with lowest preference? No, try the next one.

If a user doesn't exist on that connection it wont retry.


All mx records for a domain must be able to accept and deliver mail for all addresses on that domain... it may have to get sent over to other servers, but each MX cant just be for some users.