esshup,
It's not illegal to use steel or aluminum for a mailbox post per the USPS website, but they suggest not going over 2" OD steel pipe. It is a suggestion just like not to use milk cans full of concrete...
I think the breakaway design we discussed way back has a lot of merit, but also think that 4" OD hunk of pipe can look ominous and threatening to the untrained eye if they don't know the mechanics involved. A short internal tether between the two pieces would pretty much be a must tho.
The biggest problem with mailboxes up here is usually it's a post buried in the ground, then gets whacked, either by a snow plow or a car hits it and breaks the post off. Want to dig a new hole in the winter??? Not me!, so I would rather do something solid underground and surface mount the post to it. Actually, I only want to dig the hole once!
