We have a legacy Lotus Notes mail server with years of mail in user and shared mailboxes. The domains still send and receive mail, but we want to replace the server and eventually move the domains to Microsoft 365.
What's a practical way to export the existing mail so it stays accessible in Outlook? Are there tools worth considering, and how should we handle older archives?
For a direct move to Microsoft 365, look at dedicated Notes migration tools rather than trying to convert everything by hand. Cloudiway, Quest Migrator, BitTitan, and CodeTwo are names to investigate. Search for IBM Notes and HCL Notes as well as Lotus Notes when checking current product documentation.
Before picking one, ask each vendor exactly what it supports for your version, shared mailboxes, permissions, and local archives. A tool that handles live server mailboxes may not cover offline archive files. Run a small test and check the messages, folders, attachments, and dates in Outlook before committing to a full migration.
If the temporary mail server supports IMAP and you can expose the Notes mailboxes through IMAP, imapsync is one possible route for copying mail between servers. Test access and compatibility first rather than assuming every mailbox and folder will transfer cleanly.
Another route to investigate is a tool that can read NSF database files and export messages as EML or Maildir. You would then need a supported way to import those messages into the destination. Neither route automatically solves access to local archives, so inventory those separately.
Start with an inventory before choosing the export format. Count the active and shared mailboxes, find out where the archives live, and check who needs access to what. A sample migration should include an old mailbox and an archive, not just a small active account.
Keep the source data available until you've checked the migrated mail and agreed on what can be retired. Also get whoever owns records retention and legal obligations involved before deciding to keep or delete decades of mail. Long retention can create its own discovery burden, but the right policy depends on the organization.
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Also ask whether the tool can migrate to your proposed temporary server, or only to the eventual Microsoft 365 destination. That could affect whether it's worth moving the mail twice.