How do you require written notice from tenants?

[Joshua Morgan]

We are all about trying to automate, systematize, go-paperless, as much as possible. How do you accept written communications from your tenants? 

For example, when requiring a written Intent to Vacate notice form, do you: 
1) require they snail mail it to your management address?
2) use docusign or similar to handle electronically?
3) Use a service like Jotform to send out a signable form?

While we're currently house-hacking, it seems silly to have them snail-mail such documents. However, we don't want to start a precedent of receiving physical copies in a drop box. What have you found works well for receiving written notifications, signed acknowledgements, etc from tenants?