TLS certificate for sendmail

Getting the certificate:

apt install certbot
certbot certonly --webroot
#domain name: pomo.komputilo.org
#webroot for pomo: directoy apache serves for http://pomo.komputilo.org

To install the certificate in sendmail, insert into /etc/mail/sendmail.mc (partially copied from sendmail.org, and letsencrypt.org):

define(`confCACERT_PATH',  `/etc/letsencrypt/live/pomo.komputilo.org')dnl
define(`confCACERT',       `/etc/letsencrypt/live/pomo.komputilo.org/chain.pem')dnl
define(`confSERVER_CERT',  `/etc/letsencrypt/live/pomo.komputilo.org/cert.pem')dnl
define(`confSERVER_KEY',   `/etc/letsencrypt/live/pomo.komputilo.org/privkey.pem')dnl
define(`confCLIENT_CERT',  `/etc/letsencrypt/live/pomo.komputilo.org/cert.pem')dnl
define(`confCLIENT_KEY',   `/etc/letsencrypt/live/pomo.komputilo.org/privkey.pem')dnl
define(`confAUTH_OPTIONS', `A p y')dnl