Hi all!
Just in case somebody else runs into the same problem (and that sombody might be my future self searching the list archive):
When kmail does not work with TLS/SSL connections and you find in ~/.xsession-errors lines contaning this:
WARNING: TLS_client_method not defined! WARNING: SSL_CTX_new not defined!
... then make sure "apparmor" is not installed. It tured out that the "apparmor 3.0.6-1" blocks some functions of libssl.so.* from beeing found by kssl.cpp / ltdl.c which results in a non-funtional TSL/SSL connection.
Nik
-- Please do not email me anything that you are not comfortable also sharing with the NSA, CIA ...