Migrating to Office 365

Copper Contributor

I have been using the desktop version of Outlook longer than many of the fine forum members here have been alive. After decades, I am considering moving my email to the cloud. The primary reason is that I find myself evenly split in time spent on email with my notebook and desktop PCs and I tire of using Remote Desktop to access the singular location of my PST file. I also answer email on my phone a fair bit, and those emails never make it back to the nest. For these reasons, I think I should try moving my email to the cloud, where all of my devices will be pinging the same source.

That's what my head tells me, anyway, but I really have no idea what I'm talking about. What is involved in moving a traditional PST-based desktop email system to Office 365? Why would I want to do this and why might I not?

And should I conclude that this is worth a try, what is the recognized best practice for getting my rather large PST file up in place for O365?

3 Replies

Are we talking about only one account, yours, or multiples? Generally speaking, relying on PSTs is just waiting for disaster to happen, so my first suggestion would be to import them all into an Exchange Online mailbox and take advantage of the Online archive functionality where possible.


You havent specified where your account is hosted though, so this might involve another migration process. There are also some other things to consider, such as total size, how much of this data needs to be accessed on a regular cadence, mobile access and so on.


Thank you, @Vasil Michev --


This is a mailbox just for me and I maintain two separate email addresses. My mail servers are hosted at SiteGround and my PST file is about 5G (uncompressed and with nothing cleaned out of Deleted Items -- it would probably shrink down to about half that were I to prepare it for migration).


I have no experience with Exchange Online but am certainly willing to explore it. So I will be grateful for your continued advice.

OK, so for a single mailbox and such size, you should be fine with dumping all the content into the "main" mailbox, no need for Online archive. This has the added benefit that it immediately addresses the mobile problem (as Online archives are not accessible via the mobile apps). The rest is basically deciding which Office 365/Exchange Online plan is best suited for you, and performing the migration via Outlook's export/import functionality.


Even better, you can sign up for a free trial, experience the service for 30 days and decide whether it's a good fit for you. Keep the original mailbox up and running and use the PST export method to utilize the new one, and optionally configure some form of forwarding so that new mail ends up in the O365 mailbox as well (without having to redirect the MX record).