How do I export Thunderbird inbox mail into my Microsoft Exchange Server Inbox?

To export Thunderbird emails back to Microsoft Exchange Server, use Thunderbird's "ImportExportTools NG" add-on to export the emails as .eml files. Once exported, use a tool like "MFCMAPI" to import the .eml files into your Exchange inbox. This method avoids the size limit and restores emails for IMAP access.

To export Thunderbird mailbox to Microsoft Exchange Server inbox, first, use the "ImportExportTools NG" add-on in Thunderbird to export the mailbox as an MBOX file. Then, use a third-party tool like "MBOX Converter" to convert the MBOX file to PST format. Finally, import the PST file into Microsoft Exchange using Outlook’s Import feature or PowerShell. This process allows you to restore the mailbox content back to Exchange for IMAP access.