mailx -v -s "$subject" -S smtp=$smtphost -S from="$mailfrom" -S smtp-auth-user=$smtpuser
 -S smtp-auth-password=$smtppwd $emailto </dev/null

lrwxrwxrwx 1 root root 18 Feb  9 20:07 /etc/alternatives/mailx -> /usr/bin/bsd-mailx

bsd-mailx                   install
fetchmail                   install
procmail                    install
rmail                       install
sendmail                    install
sendmail-base                   install
sendmail-bin                    install
sendmail-cf                 install
sendmail-doc                    install

mailx: illegal option -- -
Usage: mailx -eiIUdEFntBDNHRV~ -T FILE -u USER -h hops -r address -s SUBJECT -a FILE -q FILE -f FILE -A ACCOUNT -b USERS -c USERS -S OPTION users

mailx: invalid option -- '-'
usage: mailx [-dEIinv] [-a header] [-b bcc-addr] [-c cc-addr] [-s subject] to-addr ...
             [-- sendmail-options ...]
       mailx [-dEIiNnv] -f [name]
       mailx [-dEIiNnv] [-u user]

sudo update-alternatives --set mailx /usr/bin/heirloom-mailx

sudo update-alternatives --install /usr/bin/mailx mailx /usr/bin/heirloom-mailx
60 --slave /usr/bin/mail mail /usr/bin/heirloom-mailx

sudo update-alternatives --set mailx /usr/bin/heirloom-mailx