healthchecks_healthchecks/templates/docs/email.html

<h1>Email</h1>
<p>As an alternative to HTTP/HTTPS requests, you can "ping" checks by
sending an emails to special email addresses.</p>
<h2>Use Case: Email Delivery Monitoring</h2>
<p>Consider a cron job which runs weekly and sends weekly email
reports to a list of e-mail addresses. You have already set up a check to get alerted
when your cron job fails to run. But what you ultimately want to check is if
<strong>your emails are getting sent and delivered</strong>.</p>
<p>The solution: set up another check, and add its email address to your list of
recipient email addresses. Set its Period to 1 week. As long as your weekly email
script runs correctly, and there are no email delivery issues,
SITE_NAME will regularly receive an email, and the check and will stay up.</p>