DavMail 6.7 has been released as a bugfix update for the open-source Exchange and Microsoft 365 gateway, adding PhoneAppOTP support for TOTP-based multi-factor authentication and continuing the project’s ongoing Microsoft Graph backend work.
For those unfamiliar with it, the project acts as an intermediary between Microsoft’s servers and desktop clients, providing standard protocols such as IMAP, POP, SMTP, CalDAV, CardDAV, and LDAP. This allows users to connect clients like Thunderbird instead of relying solely on Outlook.
The main addition in DavMail 6.7.0 is PhoneAppOTP support for MFA authentication. This is relevant for Microsoft 365 environments where accounts require time-based one-time passwords generated by an authenticator app.
Regarding the Microsoft Graph backend, the release includes initial support for event message retrieval and search, free/busy data handling, meeting responses, all-day events, attendee updates, modified occurrences, and recurrence management.
Additional enhancements address immutable IDs, folder requests, message header parsing, task status conversion, and throttling when Microsoft services return 503 errors.
Calendar support includes several CalDAV-specific fixes. DavMail now detects and ignores Thunderbird fake PUT requests, XML-encodes subfolder display names, applies a timezone ID fix to VTODO entries, and reduces unnecessary warnings for missing items.
Office 365 authentication handling has also been updated. The default redirect URI now uses Microsoft’s native client URL, as required by live.com authentication, though users may override this with localhost in manual authentication mode.
For EWS, DavMail 6.7 corrects an existence-condition check and restores task-to-VTODO status mapping logic to the EWS Exchange session implementation.
Finally, the update introduces several general maintenance updates, such as a fix for message file encoding regression, improved encrypted string error reporting, Ant build file typo corrections, and updated Linux setup documentation.
For more details, see the announcement.
