I need to serve someone papers, and I need to be able to prove that I served them. It is an acceptable method to drop them off at their homes mail box, but then if contested I wouldn't be able to prove it. Is it legal to have a friend take a video of me delivering the envelope, on a cellphone?
It is illegal for anyone other than the USPS to put mail in someone's mailbox *.
By law, a mailbox is intended only for receipt of postage-paid U.S. Mail.
* Except for newspapers on Sunday
The Postmaster noted an exception to the general rule: newspapers can be placed in mailboxes only on Sunday; a non-delivery day for the Postal Service.