Well I have searched some of the possibilities to install command line mail clients but there are no easy ways to install. Is this even possible without compiling the mail client ?
Funny thing, almost 3 years later I am unable to find any progres regarding answering that question, today at LibreElec.
If it helps someone: to send an e-mail from my LibreElec Raspberry Pis, I ssh to my router and send an e-mail using the router. This is absolutelly the simplest solution. Actually, I consider that way beter than using separate mailers on separate (and different) systems. This way, I allways use the same syntax and the same program in the same way - regardles of the device sending me an e-mail.
Workaround can make use of any other device capable of doing it, it needent be a router. Obviously, you need to have such a mail sending device.
The actual code from my RPi script and Asus routers is (minus the obvious variables and with ssh keys allready authorised):
echo "Subject: Msg from Raspberry" > mail.txt echo "From: email@example.com" >> mail.txt echo "Date: `date -R`" >> mail.txt cat mail.txt | ssh firstname.lastname@example.org "/usr/sbin/sendmail -S"$MAIL_SERVER" -f"$MAIL_TO" $MAIL_TO $MAIL2_TO" rm mail.txt
A reminder: for the script to work from RPi LE autostart.sh when RPi is booting, one must use /storage/mail.txt (and not the relative form as in simplified sample above).