How to redirect Kerio Outlook Connector’s automatic update to another Webserver

This article describes a way to download Kerio Outlook Connector's updates from another server.


This article works with Kerio Connect 7.4 and newer


Downloading update packages can slow Kerio Connect server down. So, redirecting this traffic to another server may help improve Kerio Connect's performance.

Technical background

When Kerio Outlook Connector asks for a new version, the Kerio Connect's response contains the "DownloadURL” property, which contains an URLUniform Resource Locator is the address of a web page on the world wide web. pointing to a directory with a new version of Kerio Outlook Connector. By default, this URL points to a special directory on Kerio Connect server, which contains update packages.

Editing configuration files

It is possible to change the URL by the "AlternateDownloadURL” variable in Kerio Connect's configuration file, mailserver.cfg. There are separate variables for Kerio Outlook Connector with Offline cache and Kerio Outlook Connector without offline cache in proper tables. The variable for the Kerio Outlook Connector with Offline cache is in the "KocOffline” table. The variable for the Kerio Outlook Connector without cache is in the "Koc" table. Those variables are empty by default. Below is an example of the default table for Kerio Outlook Connector with Offline cache.

<table name="KocOffline">

<variable name="MinParsedMessageSize">4096</variable>

<variable name="AlternateDownloadURL"></variable>

<variable name="UpgradePolicy">4</variable>

<variable name="DowngradePolicy">5</variable>


Format of URL






The URL has to end with slash "/" or backslash "\" character!

Those URL are tested in Kerio Connect 7.4 and work fine.

The URL smb://shared\folder\ is not tested and probably won't work. You can use the file://\\shared\folder\ one instead.

Required data

The new update directory has to contain all files required for automatic update of Kerio Outlook Connector. It is necessary to copy all *.exe, *.tgz and *.sig files (for the required type of Outlook Connector plugin) from the original Kerio Connect's directory to the new update directory. The original directory is as follows



It is necessary to update those files after each upgrade of Kerio Connect server.