Well, I take it
/usr/bin/php /var/www/html/tsl/email1.php
works when you run it from a terminal/command-line ? if so, good
Next, are you 'tailing'/checking /var/log/syslog to see if anything useful comes up there ?
I am assuming here you dont have /etc/cron.allow or /etc/cron.deny files that are blocking your user - on a new Ubuntu install, it's unlikely, but worth checking for
btw, I hope you're using 'crontab -e' or 'sudo crontab -e' to edit your file, strange things may happen if not