From the recipient screen in our app you can click in the box labled "add or find an address". Type in a name, then click "Add recipient name". Next click "I know their address" at which point you can enter the zip code and proceed with manually entering the address. If you like you can also click the icon on the top right which looks like an opened book. This will take you to your phone's contact list where you can choose a person and select their address to have it copied into our app.
You can also import addresses from an Excel spreadsheet, Gmail, or Outlook by logging into www.sincerely.com/account/. Select "My Address Book" at the top of the page and then click on "Import Addresses" partway down the page.
If you have further questions please send an email to email@example.com