I am using GoDaddy for my email hosting, but I was having trouble sorting through the numerous heartbeat & maintenance routines I was receiving. After coming across http://baumbach.com/google-script/ I was able to get notifications working. The largest advantage to this method is a unique schedule for each customer, so you can customize it to only alert you if there is a problem. For example, I have clients who do not use their machine every day, then a notification of a missing heartbeat on those days is worthless. I can customize that client to alert me if I have not received a heartbeat every 3 days instead of every day.
1. Sign Up for Gmail
2. Forward your existing email to this account (GoDaddy has a "Remote Email" Tab under Personal Settings)
3. Open this spreadsheet (https://docs.google.com/spreadsheet/ccc?key=0AnNsZ06J1jY2dDM5SUZqYkQ5Q1ZRcWh6OVFxVVUwTHc#gid=0) and make a copy (File, Make a Copy)
4. Head to https://www.google.com/script/start/ and "Start Scripting"
5. Copying and paste the code from http://baumbach.com/google-script/
6. Open your new spreadsheet and look in the address bar for your public key
7. Modify "var sheet = SpreadsheetApp.getActiveSheet();" to say "var sheet = SpreadsheetApp.openById("YOUR_KEY_HERE").getActiveSheet();"
8. Customize your spreadsheet and add your customer alerts
9. Add a trigger (In Google Apps Scripts) to run on a predefined schedule.
Voila! You will now receive predefined emails about missing heartbeats.