Great news - it looks like the email on store update failure works fine...
I just got an email like this:
This is to inform you that the automatic update on your website (www.xxxxx.com) has failed. Please see the error message(s) below:
ERROR: - err_au_locked ## 1300113782-0,
auto_update: err_au_locked ## 1300113782-0
I went to the site and clicked the update products and settings button, and it worked fine, so I assume this is a temporary problem and no further action is required?