A properly configured Linux system should be able to send emails from the shell using the mail command.

Using mail and at provides a handy way of sending reminders to yourself.

Example:

echo "mail -s 'Remember to buy eggs on your way home' bob@example.com < /dev/null" | at 16:30

At 16:300, this will send an email to bob@example.com with the subject Remember to buy eggs on your way home and an empty body.