Send email alert to old email address upon update of the field

To send an email alert to the old and new email address you can create a Workflow that captures the old email address and send an email alert once the record has been submitted. Below are steps to a sample workflow that sends an email alert to the old and new email address that was updated in the employee record.

Steps
1. Create a new workflow with the following details. (Customization> Workflow > Workflows > New)
 a. Name: Employee Email Update Alert
 b. Record Type: Employee
 c. Initiation: Event Based
 d. On Update: Checked
 e. Trigger Type: All

2. Add 2 new fields on the workflow.
 Field 1:
 Label - Old Email
 Type - Email Address

3. Create a new State and put a check mark on "Do Not Exit Workflow".
*Note: The "Do Not Exit Workflow" makes sure that the stored old email on the workflow is not lost or retained within the workflow.

4. Add a Set Field Value action to the state with the details below.
 a. Trigger On: Before Record Load
 b. Parameters> Field: Old Email(Workflow)
 c. Value> From Field> Record: Current Record
 d. Value> From Field> Field: E-mail

5. Add 2 Send Email action with the details below.
 Send Email 1
 a. Trigger On: After Record Submit
 b. Condition: Workflow:Old Email != E-mail
 c. Parameters> Sender> Specific Sender: Designated Sender
 d. Parameters> Recipient> From Field> Record: Current Record
 e. Parameters> Recipient> From Field> Field: Old Email(Workflow)
 f. Content: Use Template or specify email contents (e.g. "This is email is no longer associated to your Employee record.")

 Send Email 2
 a. Trigger On: After Record Submit
 b. Condition: Workflow:Old Email != E-mail
 c. Parameters> Sender> Specific Sender: Designated Sender
 d. Parameters> Recipient> From Field> Record: Current Record
 e. Parameters> Recipient> From Field> Field: E-mail
 f. Content: Use Template or specify email contents (e.g. "Your employee record has been changed. Emails will now be sent to this email address.")