How To Migrate 80GB Of Emails To O365?

Hi All,
Here's the facts before my question:
>I have a client using Thunderbird to manage their emails
>There are 2 Users, on 2 separate computers
>Both have their email setup as IMAP
>Through a convoluted setup, User 2 can access User 1's local email folders which are stored on User 1's computer
>Total Email space taken by User 1's emails is ~85GB including the local folders (local folders ~40GB)

I would like to migrate them to O365. The problem is after converting the local folders in Thunderbird emails to a PST, how can I setup those emails so both can be accessed efficiently by both Users?

*I don't think uploading a massive 85GB PST file, then sharing the folders with the other user in Outlook would be the best solution.

Any suggestions would be appreciated!
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Depends on the license of Office365 that you're going to get:

In general, I would separate data that needs to be accessed by both users and upload this data to Public Folders.
Afterwards upload/import the reduced-size PST to the mailbox.

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Kurt SutulaCommented:
Maybe you could create a shared mailbox, import some of the data into that and then grant the user full control to that.  It's just a thought.
David FavorLinux/LXD/WordPress/Hosting SavantCommented:
If I understand correctly what you're asking, you'd like to migrate your mail from one IMAP server to another (O365). performs this function.

You just aim it at a source + target IMAP server to clone email messages along with folder structure.

For your custom way one user is accessing another user's folder, I'd skip trying to play this type of config game with O365.

Just have the person who requires accessing two account, login both accounts.
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Lindsey SmithFreelancerCommented:

If you are looking to migrate a large amount of data to Office 365 account then the most reliable solution will be to go for a third party application. Moving 80GB of emails from MBOX file to cloud manually can cause data loss.

You can use a professional software to transfer MBOX file to Office 365 with ease.

Thanks & Regards
Lindsey Smith
PAMurilloAuthor Commented:
Thank you everyone. I'm contemplating between creating an unused email address that I can migrate the Local Folders to then shared with the two Users or migrating them to Public Folders.

I will talk to my clients some more to further understand their needs.
PAMurilloAuthor Commented:
Thanks Ronin, I think dividing up the shared folders and moving them to Public is the best bet.

Everyone else - I appreciate the  suggested tools!
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