Thunderbird to Office 365 migration can be done manually using IMAP or through an automated migration tool. Before starting, ensure important Thunderbird data like Inbox, Sent Items, Drafts, Contacts, Calendar, Attachments, and Custom Folders are properly handled. The manual method requires adding the Office 365 account in Thunderbird via IMAP and OAuth2 authentication, then moving emails using drag-and-drop. Contacts can be transferred through the Address Book, while calendars must be exported as .ics files and imported separately into Outlook Web. However, users often face issues such as OAuth authentication failures, disabled IMAP, broken folder hierarchy, mailbox timeout errors, and missing calendar sync. Because of these limitations, many users prefer automated solutions like RecoveryTools Thunderbird to Office 365 Migrator. The software securely migrates Thunderbird emails, contacts, calendars, attachments, and metadata to Office 365 while preserving folder structure. It also supports bulk migration, advanced filters, and secure OAuth login for smooth and reliable data transfer.
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