This is happening because when you set up your Workflow Rule you selected Evaluation Criteria Option #3. 

To fix this, follow these steps:

First, go back to your Workflow Rule and click on the "Deactivate" button.

Create a new Workflow Rule. But first, ask yourself these questions:

  1. Do I only want this Workflow Action to ONLY fire off once, when the record is first created and the record meets my criteria?
  2. Do I want this Workflow Action to fire off ONCE, WHENEVER the record meets the criteria? This may or may not happen when the is record is created or at any point in the records life cycle?
  3. Do I want this Workflow tool to constantly monitor my Workflow Rule as this record could change in and out of meeting my criteria over the records full life cycle. Every time the record meets the criteria, fire off my workflow action.

Options 1 & 2 are pretty self explanatory. If you choose either of these options, your Workflow Rule will only fire off its related Workflow Action once over the lifetime of that particular record, and only for records that have been "Created or Modified" within the last 30 minutes.

Option 3 is a bit more complex. Only use this option for really active records that change in and out of meeting your criteria, and when your rule criteria includes a formula field. To use this option correctly on an Email Alert, you should add at least one more filter to your Workflow Rule and and or/add at least one more Workflow Action; usually a "Field Update". The new field update will be used to update the record so it no longer meets your Workflow Rule criteria. This will prevent the Workflow Action from meeting your criteria the next time our Workflow engine runs.

As an example on using Option 3 for an Email Alert. Create a new field on your object "Alert Sent". As one of your rule criteria, include the filter Alert Sent = False. And on your Workflow Action, include a "Field Update" that updates Alert Sent to True. This way, as soon as workflow fires off, this record will no longer meet the criteria and it won't fire off again the next time workflow runs. REMEMBER: Option 3 of the evaluation criteria does NOT rely on a record being edited. Options 1 and 2 REQUIRE the record to be "Created, Edited or Modified" in order for it to be considered for one of your Workflow Rules.

If you require additional explanation of how to use Option 3, please call us at (480) 696-3812. Our office hours are 8 AM to 5 PM Monday - Friday (Arizona Time) .. but call us outside these hours as it's not unusual for one of us to be in the office late nights and weekends.