Send reminder emails to Approvers after the initial Approval Process email

Preparation:

Email Template for the reminder
For existing Approval process, just add actions on both Approval & Rejection

Please follow the detailed steps below:

Step 1 - Create Email Template:

Step 1:

In Salesforce Classic (Non-Enhanced User Interface):

1. Click Your Name | Setup | Email | My Templates

In Salesforce Classic (Enhanced User Interface):

1. Click Your Name | My Settings | Email | Email Templates

In Lightning Experience:

1. Click Setup | Email | Templates

Step 2 (for all User Interfaces):

1. Select either Text, HTML, Custom or Visualforce.

2. Fill out all fields and then select Available for Use.

3. Populate the 'Name,' 'Subject' and 'Email Body.'

4. Then Save.

Step 2 - Create a Custom Field Checkbox :

Step 1

Salesforce Classic (Non-Enhanced User Interface):

1. Click Your Name | Setup | Customize.
2. Choose an Object.
3. Select 'Fields.'
4. Navigate down to 'Custom Fields.'

Salesforce Classic (Enhanced User Interface):

1. Click Setup | Customize
2. Choose an Object.
3. Select 'Fields.'
4. Navigate down to 'Custom Fields.'

Lightning Experience:

1. Click Setup | Objects and Fields | Object Manager.
2. Choose an Object.
3. Select 'Fields & Relationships.'

Step 2 (For all User Interfaces):

1. Click the New button.
2. Select Checkbox | Next.
3. Fill in Field Label - Default Value is Unchecked | Next | Next | Save.
4. Navigate to 'Page layout' and hide the checkbox.

Step 3 - Configure the Approval Process:

Salesforce Classic (Non-Enhanced User Interface):

1. Click Your Name | Setup | Create | Workflow & Approvals
2. Click Approval Processes.

Salesforce Classic (Enhanced User Interface):

1. Click Setup | Create | Workflow & Approvals
2. Click Approval Processes

Lightning Experience:

Click Setup | Process Automation | Approval Processes

Then (For all User Interfaces):

Note if you are editing existing Approval Process, please deactivate it first
Click the name of the Process
Look for Approval Steps
to add Approvers Click Edit | Next | Next
click Add Row, then assign
then choose either First response or Unanimous
Save.

1. Then for the Actions Click "Show Actions"
2. You'll see 2 Actions (Approval & Rejection)
3. For Approval Actions click the Add New, then choose Field Update
4. Put a check mark on Re-evaluate Workflow Rules after Field Change | Next | Choose FALSE
5. SAVE (Do the same Process with Rejection Actions)
6. Then Click Activate
7. Look for Initial Submission Actions
8. Click "Add New" | click “Field Update"
9. Fill in Name | for Field to Update - choose the custom field checkbox
10. Put a check mark on Re-evaluate Workflow Rules after Field Change | Next | Choose TRUE
11. SAVE

Step 4 - Create Scheduled Flow :

Step 1

1. Go to Flows.

2. Choose the Object, then click Next.

Step 2: Create a flow

1. Click New Flow button.
2. Choose Record-Trigger Flow, then click Create button.
3. Choose the Object.
4. Choose A record is created or updated in Configure Trigger.
5. Choose All Conditions Are Met (AND), then Field - Custom Checkbox | Operator - Equals | Value - True in Set Entry Conditions.
6. Choose Only when a record is updated to meet the condition requirements in When to Run the Flow for Updated Records.
7. Choose Actions and Related Records in Optimize the Flow for.
8. Click Start icon, then click Add Scheduled Paths (Optional).
9. Fill in Path Label and API Name.
10. Set Last Modified Date as Time Source.
11. Set 24 in Offset Number, and Hours After in Offset Options.
12. Click Add Element icon on your scheduled path.
13. Choose Send Email Alert.
14. Choose your email alert in Action.
15. Fill in Label, API Name and Record ID.
16. Click Save button.
17. Fill in Flow Label and Flow API Name.
18. Click Save button.
19. Click Activate it.