Logistically, something like that could save the post office a bunch of money since they don't refund postage just because it was delivered electronically.
Furthermore, people expecting a high-priority package would be more likely to log in and release it to their mailbox more quickly.
Also I wish I could opt to "block sender" for ads and other junk. The post office would still get money/postage, but I would just give the post office advanced consent to shred/recycle all mail from this sender and consider it officially delivered.