In some rare cases Postfix connect to a wrong MX server

[Msd]

Hello,

I note in some rare case that Postfix tries to deliver an email to a 
wrong MX server.

I have opened a bug to describe my problem here : 
https://bugs.launchpad.net/ubuntu/+source/postfix/+bug/1549388/

Do you know what happens ?

Thanks,


Guillaume