Email Migration from Exchange on-prem not in our domain to our Exchange Online

Hi @Wächter André,

If there are only 15 mailboxes to be migrated and the mailboxes size are not very large, you can migrate by export/import pst files.

The general steps would be like:

1.export mailboxes to pst files on Exchange server or via Outlook

2.assign licenses to create new mailboxes for these users in Exchange Online

3.import pst files into the newly created mailboxes

Below are some links with more detailed information on how to export/import pst files.

Export/Import on Exchange side:

export mailboxes to pst files on Exchange server: Procedures for mailbox exports to .pst files in Exchange Server

import pst files into mailboxes in Exchange Online: Learn about importing your organization's PST files

required permissions in Exchange Online and other FAQs: FAQ about importing PST files

Export/Import on Outlook side:

export mailboxes to pst files in Outlook: Export or backup email, contacts, and calendar to an Outlook .pst file

import pst files into mailboxes in Outlook: Import email, contacts, and calendar from an Outlook .pst file

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