EAS-4-TbSync

This provider add-on adds Exchange ActiveSync (EAS v2.5, v14.0, 14.1 & v16.1) synchronization capabilities to TbSync.

More information can be found in the wiki of this repository

Known limitations

Recurring events from a foreign time zone (±1 hour DST drift)

A recurring series can drift by one hour around daylight-saving transitions, but only when all three of these hold at once:

1. the series was authored in a time zone other than your Thunderbird default zone, and
2. the server sends no usable TimeZone blob — Z-Push, Kopano and Grommunio send an all-zero one, and
3. the occurrence falls in a different DST state than the series master.

The authoring zone is then simply not transmitted, so the series anchors to your default zone. This is inherent to what the protocol carries; the client cannot recover it.

Not affected: Exchange on any version, including 16.0/16.1 — it sends a full TimeZone blob, which is matched back to the correct IANA zone (same-offset zones such as Berlin and Paris are told apart by their DST transition dates). Single events are never affected, since their exact UTC instant is always preserved. Neither are incoming all-day events. Pushing an all-day event back to a non-Exchange server that ignores the blob we send can still shift the date by a day for users east of UTC.

Want to add or fix a localization?

To help translating this project, please visit crowdin.com, where the localizations are managed. If you want to add a new language, just contact me and I will set it up.

External data sources

• TbSync uses a timezone mapping provided by Matt Johnson-Pint

Icon sources and attributions

CC0 Public Domain

• [365_*.png] by Microsoft / Wikimedia, converted from SVG to PNG

CC-BY 3.0

• [eas*.png] by FatCow Web Hosting
• [exchange_300.png] derived from Microsoft Exchange Icon #270871, resized