This article contains modification of configuration file so it is needed to restart Kerio MailServer service.

1. Stop Kerio MailServer service
2. Open configuration file mailserver.cfg located in following directory by default:
• C:\Program Files\Kerio\MailServer on Microsoft Windows system.
• /opt/kerio/mailserver on Linux based system.
• /usr/local/kerio/mailserver on Mac OS X based system.
  
3. Locate following option in the Security section of the configuration file:

   <variable name="EnableSSLv2">1</variable>

4. Change its value to "0" as follows:

   <variable name="EnableSSLv2">0</variable>

5. Save configuration file and start Kerio MailServer service

Now is SSLv2 support disabled for Kerio MailServer service.

Note: Some email clients may not support SSLv3 and may fail to connect to Kerio MailServer due to SSL version incompatibility.