RedHat released sendmail-8.13.8-10.el5_11.src.rpm which includes sendmail-8.13.8-ssl-opts.patch which adds support for disabling SSLv3 and SSLv2 in sendmail.cf
But as far as I can see there is no support in sendmail.mc - I can't see how to compile sendmail.mc to get the required line ServerSSLOptions in sendmail.cf
Does anyone know how to do this ?