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Thunderbird 155 Improves Exchange Setup and Custom OAuth Support
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Thunderbird 155 streamlines manual account configuration for Exchange and Microsoft Graph, adds PKCE and external-browser OAuth options for IMAP and SMTP, and fixes multiple mail, calendar, and security issues.
For engineers deploying or integrating email clients, Thunderbird 155 reduces setup friction for Exchange and Microsoft Graph accounts and gives more control over OAuth flows with PKCE and external-browser support. Administrators gain new enterprise policies and cleaner OAuth token cleanup, while long-standing IMAP tag sync and search bugs are addressed.
Written by elseif from the cluster below · every claim links back to a sourceThe three things worth knowing
Custom OAuth support now includes PKCE and external-browser options for IMAP and SMTP, and OAuth add-ons can override built-in settings per domain.
New enterprise policies let administrators disable QR export and experimental features and set a default address book for manual contact additions.
Fixes include IMAP tag synchronization, search filter issues, encrypted mail draft preservation, and OAuth token removal on account deletion.
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