When adding recipients, you have the option to have them authorize themselves either when they are opening the send-out, signing the document, or both.
You have a few options for authorizing the recipient.
They can do it with a security question and answer, using their eID, or by having the recipient enter a 4 digit code before opening and/or signing the document.
When choosing the SMS option, make sure to add the recipient's mobile phone number to the contact before sending the document.
Important information regarding SMS sendings: Sending with SMS or SMS verification and signing with SMS is only available from plan Professional
Important information regarding eID: Only available from plan Professional.
How to add authorization for a recipient when opening or signing a document
Create a draft
Add your recipient
Slightly to the right under the recipient name you will see a padlock symbol next to the recipient name
Click on it
Choose the authorization method of your liking