Hosted auth, grant, and message sync fixes

October 7, 2026EmailAgent AccountsCalendarPlatform

Added

• is_owner on Agent Account event responses. Events returned for Agent Account grants now include an is_owner boolean that’s true when the Agent Account can act as the event’s organizer. See Check whether the agent organizes an event.

Fixed

Authentication and grants

• Hosted authentication page. The hosted authentication page now returns only the application details it needs to show the sign-in screen.
• Grant deletion. You can now delete a grant whose connector was removed earlier.
• Microsoft admin consent. Account lookups during admin consent now match accounts by their proxy UPN address.

Messages

• Duplicate IMAP messages in the same folder no longer cause message and thread list requests to fail.
• EWS connection and transport failures are no longer reported as rate limiting, so you can tell a provider connectivity problem apart from actual throttling.
• Messages from Microsoft Graph accounts now reliably include a Message-ID header, falling back to Graph’s internetMessageId when the primary field is missing.
• EWS message reads now retry automatically instead of failing outright when the provider’s IsDraft restriction gets in the way, improving reliability for Exchange grants.
• EAS (Exchange ActiveSync) messages no longer show garbled text in headers or body content caused by incorrectly recovered surrogate-escaped bytes.
• IMAP messages that begin with an mbox-style From line are no longer skipped when listing or syncing messages.
• IMAP folder assignments are now preserved when a folder read fails during a COPY, EXPUNGE, or MOVE operation, instead of being dropped.
• Draft updates and thread folder writes now correctly report the folders a message was saved to, and a failed write returns a mapped error instead of a generic one.
• IMAP multipart messages that can’t be split into separate parts now return correct BODYSTRUCTURE and BODY[1] responses.