Prevent duplicate email addresses from being created

There are a few options to help prevent duplicate email addresses in the org.

• Create a new/edit email address field and set this field as unique.
• Updated email fields based on a workflow rule.
• Use an app from the AppExchange

The example directions are based on the Contact object.  This is only for new records.

Option 1: Create a Unique Custom Email Address Field

Classic: 

Go to Setup | Customize | Contacts | Fields and click New

Lightning: 

Click the Gear icon then go to Setup | Object Manager | Contacts | Fields & Relationships and Click the “New” button

For both interfaces:

1. Choose the “Email” data type.
2. Click the “Next” button.
3. Give it a name.
4. Make sure you check the box next to “Unique”.
5. Click the “Next” button until you are allowed to “Save”.

Option 2: Create a Workflow Rule to Prevent Duplicates

The instructions below are to create a Workflow Rule and update the custom Email field.

1. In Classic: Go to Setup | Create | Workflow & Approvals | Workflow Rules
    In Lightning: Click the Gear icon then go to Setup | Process Automation | Workflow Rules
2. Click the “New Rule” button.
3. Choose “Contact” in the drop down.
4. Click “Next”.
5. Give it a name.
6. Choose “Created, and every time it’s edited”.
7. In the Rule Criteria section in the first drop down menu choose “Contact: Email” not equal to and then leave the value blank. 
8. Click the “Save & Next” button.
9. In the Immediate Workflow Actions section click the “Add Workflow Action” drop down and click “New Field Update”.
10. Give the field update a name.
11. In the “Field to Update” drop down choose the field you created previously.
12. In the “Specify New Field Value” section choose “Use a formula to set new value”.
13. Click the “Show Formula Editor” link.
14. Click “Insert Field”.
15. Find the “Email” field that has the Type: Email and the API Name: Email.
16. Click the “Insert” button.
17. Click the “Save” button.
18. Click the “Done” button.
19. Click the “Activate” button.

Option 3: Use an AppExchange Application for Deduplication

There are also AppExchange applications available. Navigate to http://appexchange.salesforce.com/ and search for duplicate email or dedupe or de-dupe or other search terms to find apps that may assist in preventing duplicate records.