Remove strict MX priority requirement.

[FozzieHi]

Currently there's a strict MX priority requirement for:
mx1.simplelogin.co - 10
mx2.simplelogin.co - 20

I don't think it matters what priorities these are, only that mx1 has a lower priority than mx2, this priority requirement should be removed.

[nguyenkims]

Using 10 and 20 as priorities seems to be an implicit convention in mail services. Can you tell me more about your scenario in which you don't want to set the priority to 10 or 20? For info, the MX records can only point to the same email service.

[FozzieHi]

I don't think it matters if it's 10, 20 or 1, 2 it both achieves the same goal.

I don't have a specific scenario but people may try to just add MX records with whatever priority they want and it might be a brief annoyance that they have to use 10 and 20.

[nguyenkims]

@FozzieHi I see, I just added this ticket on the open roadmap https://trello.com/c/7Gl1KXst/84-allow-other-priorities-in-mx-record, feel free to vote on it to make it happen sooner :).
I close this Github issue then.