Kerio (EAS) is sending HTTP400 instead of HTTP449 in case of unprovisioned request
I am the author of TbSync, an Exchange Active Sync Connector for Thunderbird. Many of your users are using TbSync to be able to use their Kerio calendars and address books with Thunderbird.
I had to add an extra option for Kerio to TbSync, because Kerio fails to negotiate provisioning. I would like remove that option in the next release.
As per the EAS documentation, an EAS client (like TbSync) should first try without enabled provisioning to connect to a server. The server may return HTTP 449 to request provisioning.
Kerio is not sending a 449, but a 400. Can you change that please?