Zip+4 + delivery point is for the set of mailboxes. If you each have individual mailboxes (not clustered), the 11 digit code is enough. Or house number plus scrawl plus zip+4.
We're individual units. House number was my choice, and that's 3 digits. Trying to figure out if I get it to one alphanumeric character. First letter of my last name might do it.
