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DavMail 6.7 has been released as a bugfix update for the open-source Exchange and Microsoft 365 gateway. It introduces PhoneAppOTP support for TOTP-based multi-factor authentication and continues progress on the Microsoft Graph backend.
For those unfamiliar, DavMail acts as a bridge between Microsoft servers and desktop email clients. It enables standard protocols like IMAP, POP, SMTP, CalDAV, CardDAV, and LDAP, allowing users to connect applications such as Thunderbird instead of relying solely on Outlook.
The key addition in version 6.7.0 is support for PhoneAppOTP in MFA workflows. This is particularly useful in Microsoft 365 environments where accounts require time-based one-time passwords generated by authenticator apps.
On the Microsoft Graph side, the update brings initial support for retrieving and searching event messages, handling free/busy data, managing meeting responses, supporting all-day events, updating attendees, handling modified occurrences, and managing recurring events.
Other improvements include better handling of immutable IDs, folder requests, message header parsing, task status conversion, and improved throttling behavior when Microsoft services return 503 errors.
Calendar functionality also sees several CalDAV-related fixes. DavMail now ignores Thunderbird’s fake PUT requests, properly XML-encodes subfolder display names, fixes timezone IDs in VTODO entries, and reduces unnecessary warnings about missing items.
Authentication for Office 365 has been updated as well. The default redirect URI now uses Microsoft’s native client URL to meet live.com requirements, though users can still override it with localhost when using manual authentication.
For EWS, the release fixes an existence-condition check and restores task-to-VTODO status mapping within the Exchange session implementation.
Finally, the update includes general maintenance fixes, such as resolving a message file encoding regression, improving error reporting for encrypted strings, correcting typos in Ant build files, and updating Linux setup documentation.
For more details, see the announcement.
