#log into the mail server
echo "This is the body of the email." | mailx -v -s "This is the subject" -S smtp="smtp:my.domain.com:587" -S smtp-use-starttls -S smtp-auth=login -S smtp-auth-user="me@my.domain.com" -S smtp-auth-password="password" -S ssl-verify=ignore recipient@my.domain.com

mailx: illegal option -- S
Usage: mailx [-EiInv] [-s subject] [-c cc-addr] [-b bcc-addr] [-F] to-addr ...
       mailx [-EHiInNv] [-F] -f [name]
       mailx [-EHiInNv] [-F] [-u user]
       mailx -e [-f name]
       mailx -H