I use the Kaspersky Internet Security and Thunderbird email client for several years without problems together. In the 2015 version, however, appeared on the problem that although provided in the Internet Security release, Thunderbird is blocked. Upon request, the Kaspersky support I received the following reply: Dear customer, We apologize for the inconvenience. The supported e-mail programs for Kaspersky Internet Security 2015: MS Office Outlook 2003 MS Office Outlook 2007 MS Office Outlook 2010 MS Office Outlook 2013 MS Outlook Express (Windows Mail) Please read the requirements, which are located on the following Web page, by [...] Should any questions arise, please contact us again available.
Addendum Kaspersky 25/08/2014.
Dear customer, The Thunderbird program is not supported and is not compatible. For more information, please visit: [...] Many Thanks.