Yes, you can have the writers send their letters via internet, or mail it manually. When filling the application, at the section of LoR, you'll have 2 options: send via internet or mail. AASDAS will send the writer a link if you request to be sent via internet. If send by mail, there's a form that need to be filled out and mailed with the letter. The form just ask for your personal information so they know it's for such as your AASDAS ID, name, DOB, etc...