How to add sent letters to a campaign?

To add previously sent letters to a campaign, follow these steps:

1. In the 'Letters' section, click on 'All Letters' from the left sidebar.

2. Click on 'Status' and use the dropdown menu to filter the letters by their current status.

3. Select the letters you want to add to your campaign.

4. Click 'Add to Campaign.'

5. Choose to add the letters to an existing campaign or create a new one.

6. To view the campaign, click on 'Campaigns' in the left sidebar and select the campaign you added the letters to.