Explicitly disable SSL / TLS for a host when sending email via sendmail
Once the sendmail mail server is configured with its own SSL certificate it will try and initiate TLS/SSL connections with all other SMTP servers if they advertise supporting TLS or SSL.
If you really need to send mail to a SMTP server that has a broken SSL configuration, sendmail can be configured to explicitly not attempt a secure connection but to instead deliver mail in using plain text.
To do this, edit your
/etc/mail/mailertable and add an additional line in the format below:
To activate the new config the mailertable database will need to be rebuilt, which can be done by:
cd /etc/mail makemap hash mailertable < mailertable
Last updated: 14/10/2015