Set birthday reminders two hours before the Contact's birth date

In Salesforce Classic: Setup | Create | Workflow & Approvals | Workflow Rules | click New Rule
In Lightning Experience: Gear icon | Setup | Process Automation | Workflow Rules | click New Rule


Step 1: Select object - Contact (select the object from the drop-down) and click on Next.

Step 2: Configure workflow rule 

1. Edit Rule section – Enter the rule name
2. Evaluation criteria section – Select the radio button Created
3. Rule criteria section – Run this rule if the following drop-down Criteria are met
4. Field drop-down – Contact: Birthdate is not equal to null and Contact: Email is not equal to null.
5. Click on Save & Next button.

Step 3: Click on the Add Time Trigger button, in the workflow time trigger edit page

1. Enter the hours as 2 before Contact Birthday and click on Save button.
2. Finally click on the Done button.

Step 4: Specify workflow action

1. Click on Add Workflow Action drop down button and select New Email Alert
2. Edit Email Alert Section - Enter the following:

• Description
• Email Template (lookup Field)
• Recipient Type (Multi select box)
• From Email Address (Drop down box)             

3. Click on Save button

Note: Always check if the workflow rule is activated

See also:
Create a Workflow Rule