When sending a message that contains a link, you may want to include some subscriber data in the URL. You can do this using the Make URL safe option when inserting subscriber data.
Steps
Create a new message.
Add the URL you want to send.
Click the Insert Subscriber Data (or person) icon.
Select your attribute from the list (i.e. First Name, Last Name). You can also choose a fallback option if that data is missing from the subscriber's profile.
Click Additional Settings and check Make URL safe.
That's it! When you send or schedule your message, your link will safely contain subscriber data.