TLS handshake error

[Bob Bish]

This problem has still not been resolved after almost 4 weeks. Several address, at several different domains, continuously bounce with the reason:

(reason: 403 4.7.0 TLS handshake failed.)

From what I understand about this, the mail server on which the lists reside is somehow detecting TLS capable incoming mail servers and is requesting a secure connection. This needs to be turned off.
For the record, I manage mailing lists which reside on donated server space. I do not run the server itself, so do not have access to its configuration. Any questions about that should go to the guy who does:

[EMAIL PROTECTED]

He runs sendmail (not sure what version) using Linux 2.4.18-17.7.x
Would anyone know how to fix this?

...Bob