Asking customers for larger mailboxes?

[muttleycrue]

I was lead to believe that asking or telling a customer to put up a bigger mailbox was not allowed, way back in my early years as a carrier.
Is this an actually policy? Or am I misremembering?

Would appreciate if anyone could provide policy (if it exists) stating that asking/telling customer to install larger mailbox - or, by extension, a box or shed at the mailbox for parcels - is not acceptable.

 

[Rt2mailman]

Unless the customer's house is beyond 1/2 mile from your route's line of travel, why would you not deliver their parcels and receive credit for your route evaluations?
You can request anything from your customers, but you can only require their box size is adequate enough to accept the average of their daily amount of mail.