You can’t spend every waking minute and second looking at the data for all of your sites. When something goes wrong, you need to be aware of it, and it shouldn’t have to wait until your next opportunity to look at it. Setting up email alerts allows you to receive a notification when something is wrong.
For example: Recently we discovered that Google is now penalizing sites with a high bounce rate. For this reason, we set up email alerts on all of our customers to notify us when one of our sites rises above a healthy bounce rate.
You can’t rely only on Google Analytics to alert you when something is wrong with your site. For most errors and issues, it’s best to rely on Google Webmaster Tools. But it can be time consuming to check all of your customers on Webmaster Tools. Save some time and set up custom email alerts when a site is flagged with an error or issue.
Email alerts aren’t only for the bad news. You can set up alerts for positive happenings as well as negative ones. For example, if one of your clients has a certain quota or goal they would like to meet, you can set up email alerts to notify when this has been met. On the other hand, if you have a regular frequency of goals or purchases, you can set up email alerts for when goal completions or purchases drop below a threshold over a given span of time. This gives at least some clue as to when something breaks or is not performing as usual. You can set up email alerts to notify you of positive trends, such as a quota met, or a larger than usual sale. These kinds of email alerts makes it easier for you to highlight the successes of your efforts.