During the process of migrating from our existing email provider to O365 we will need to change our MX records... specifically, the MX record priority and the Autodiscover address.
It will likely take us a few days to get everyone migrated over to O365 (i.e. to export their existing PST file into their new Outlook account for O365).
Question 1: Can we set up an Autodiscover address BEFORE adding the new MX record(s) for O365? If so, this will help us immensely in setting up the new accounts in Outlook.
Question 2: Can we have essentially 2 sets of MX records, with different priorities, so that it will be "invisible" to end-users of when the new MX records take effect? That is, they can continue to send and receive in their OLD Outlook account *OR* their new Outlook account based simply on the priority? We would like to give them the comfort that they will not experience any downtime with regard to being able to send or receive emails. Then, once we are sure the new MX records have become effective, we can simply adjust the Priority and instruct them to start using the new account exclusively, and then we can import their old PST file into their new O365 account?
Apologies if my questions are not clear... and please feel free to offer conversion suggestions. We're only talking about 25 mailboxes, but their emails are mission-critical and downtime/interruptions are to be avoided as much as possible.