emClient -> WebDAV -> Kolab 16

I have a Kolab 16 server setup, which sits behind a Reverse Web Proxy.  The connection is SSL from eMClient to the reverse web proxy, then clear port 80 from the reverse web proxy to the Kolab 16 server.

I can create an item in the calendar without any problem. But as soon as I need to update anything in the item (changing date, time, snooze the item, that kind of thing, I’m getting an error saying that the service is unavailable, which is, indeed, not true.  This somewhat makes the webDAV interface unusable.

I have the same issue wheter I’m in the calendar module or the addressbook module…

Following is what I see from eMClient. 

This is a screenshot from eMClient 7 Beta. I have the exact same issue on eMClient 6.

Can someone help me with this one?


Christian Tardif

Hello Christian,
I believe the proxy might be the cause of this issue, but we can set up CalDAV logging and analyze the server reply.

Go to Tools>Settings>Advanced section and check the the logs for this WebDAV.
Restart eM Client.
Replicate this issue on a test event.
Send the logs to rust@emclient.com with a link to this forum topic and ideally the EML file of the test event.

Thank you.


Hello Christian,
I looked through the logs and it really seems that the Server becomes unavailable - The service is temporarily unavailable (Cache failure) is the message directly from the server.
The problem could be either with the server or the proxy - can you make an exception for eM Client or use an external tool like Proxifier to bypass the proxy?


Hi Olivia,

Just for the sake of testing, I completely bypassed the reverse proxy. Now, I’m talking directly with the webserver, and I’m getting the exact same result. As soon as I update a contact or an event, emClient comes back right away telling that the server is unavailable. But looking at the logs at the exact same time, I can tell you that the server is available. It answers to other requests. Right after an issue, I can create a new event that will be saved without issue to the kolab server. It’s always after any modification.

I’ll send you the logs via email with my last tests. Maybe you’ll see something.