Question : MX record priority - want to raise priority and want to be sure

I'm faxing through a priorty ordering for MX records to an ISP on behalf of a company and although I'm sure I'm right I wanted to get a second opinion before going ahead.

Currently they have
mail1.example.com = 10
mail2.example.com = 20

I want to swap these round but as I have to fax over the request and they take a little while to action  don't want to get it wrong.

therefore instead of aksig them to swap I'm just going to ask them to change mail2.example.com to have a priorty of 5.
Therefore it will become

mail1.example.com = 10
mail2.example.com = 5

Is there anything wrong wtih this approach? I just want to be sure that values above 10 do not have any special meaning or anything weird like that. I know it seems straight forward, but I really don't want anything to go wrong as I never see other domains below 10.

Thanks in advance.

Answer : MX record priority - want to raise priority and want to be sure

Hi,
 
You should be find records can go below 10. I have not been 100% sure why they have always started at 10; other than it used to be common practice in programming when line numbers were important to increase the line numbers in 10s so you could slot in other lines if neeed at a later date.

One thing to note though is that once they have performed the change DNS Servers which already have the record cached will take sometime to update the cache in line with the Time To Live (TTL) set on the DNS Records.

This can be any value but is commonly 24 hours.

Adam