Email Migration to Office 365

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.

Thank you,
K AAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Vasil Michev (MVP)Commented:
1) Yes, you can. If moving from another Exchange server however, this can cause you some trouble - credentials prompts, issues with free/busy, etc.
2) Yes, no problem there as well.

What kind of migration will you be performing?
K AAuthor Commented:
Thank you for your reply.  Regarding What kind of migration will we be performing, I'm not sure how to answer that, other than to say that we'll create the new mailboxes in O365, then go into each user's Outlook and add the new account, change the MX records, then when the new MX records have taken effect and no new emails are going into the old account, we'll import the user's PST file into the new O365 account in Outlook.  Is that the best way to proceed?

Am I correct in understanding that we can just IMPORT the existing PST file instead of EXPORTING to a new, fresh "offline" PST file and import that?  IF so, that would save a LOT of time.
Vasil Michev (MVP)Commented:
There are far better methods of doing the migration, compared to PST export. But they have certain requirements, so might not be applicable in your scenario. You can review them here:

If PST migration is the only option, you can still automate the process by using the free PST Capture tool ( or some paid 3rd party tools.
Become a CompTIA Certified Healthcare IT Tech

This course will help prep you to earn the CompTIA Healthcare IT Technician certification showing that you have the knowledge and skills needed to succeed in installing, managing, and troubleshooting IT systems in medical and clinical settings.

K AAuthor Commented:
Thank you, Vasil... It looks like the 1st option you listed is based on starting with Exchange, either on-premise or hosted, as the SOURCE.  IF so, that's not the case for us:  we're using a plain old POP3 emailbox provider.

The 2nd option looks promising, however.  It would seem that we would be able to use this no matter whether we are currently using Exchange or not.  If that's the case, then this could work for us... BUT it would seem to me that it would be MOST valuable in an organization where there are many, many mailbox users, all in one physical location so that the PST files can be accessed centrally... for us, that is not the case - we have about 20 users in 4 different locations, so, short of setting up everybody with a VPN, and since we have to connect to everybody's computer anyway (to either install the PST agent and set up a VPN connection, or just start the PST import process), it would seem that we might just be better off doing it the old fashioned-way.  Would you agree?
Vasil Michev (MVP)Commented:
If migrating 20 users from POP server, PST export/import is the best option indeed. Or you can even avoid that by configuring both the old and the new accounts in the same Outlook profile and copying the mails directly between the mailboxes.
K AAuthor Commented:
Thank you again!  But you can save me a few minutes... if we do the "copy" process, doesn't that have to be done "folder-by-folder," one folder at a time?  If so, it would probably be faster in this case to do the full mailbox import...  thoughts?
Vasil Michev (MVP)Commented:
Up to you, and up to the user. Some people prefer to keep all mail in the Inbox, so you really need to only copy Inbox, Sent and Deleted Items for them. Others are extensive (sub)folder users, and for them of course it will be more appropriate to do the mailbox export.

In any case they can keep both the old and new mailbox for some time in Outlook and do the migration over time. Usually a good idea is to do it right before leaving the office or going for lunch, as doing the copy will 'lock' Outlook.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
K AAuthor Commented:
Excellent, and thank you for sticking with me.  Good, clear answers.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Office 365

From novice to tech pro — start learning today.