I e-mail bombed myself once
Many years ago I set a cron job to execute every few seconds (ironically to change my e-mail signature!!).
For some unknown reason during the night the cron job was no longer able to execute.
As those of you who know cron better than me will know it then sends an e-mail letting you know it failed (I know, I know, you can probably disable this feature but I had/have no clue how).
When I came in in the morning I had thousands of e-mails from me telling me my e-mail sig changing cron task had failed to execute.