[Exim] problem using tls_verify_hosts parameter

Hello,
I am playing around with server side TLS configuration
at the moment. TLS in general is working but now I want
to use the tls_verify_hosts parameter to improve security,
which doesn't work at all.
The Exim debug log shows an "peer did not return a
certificate" error. I searched through the mailing list
archive and found some postings about it but no solution
for this problem.
Now I wonder if it is a well-tested function or if it is
still in development.
Has anyone successfully enabled this feature and can give
me a hint how to configure different email clients to
send a certificate?

Regards Juergen Edner
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Mail: juergen.edner@???
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