simple smtp client solution
docker build -t email-sender . docker run --rm \
-e SMTP_HOST="your_smtp_host" \
-e SMTP_PORT="587" \
-e SMTP_USER="your_smtp_user" \
-e SMTP_PASSWORD="your_smtp_password" \
-e SMTP_FROM="your_smtp_user" \
-e EMAIL_TO="smtp_target" \
-e EMAIL_SUBJECT="your_email_target" \
-e EMAIL_BODY="your_message" \
email-sender