Separate mail boxes for new duplex

[Christopher Cole]

I'm closing on a house that used to be a single family, but was converted to be a duplex. There is still only 1 mailbox, however.  It seems previously all mail went to the same box, and then the tenants split it among themselves.

I'd like to add a second mailbox and have them be Unit A and Unit B or something like that. There doesn't seem to be much information about how to do this with USPS though. Does anyone have experience with this?

[Christopher Cole]

I'm glad to see this post has helped so many people over the years.  I guess I'll just follow up real quick - I did indeed just setup another mailbox, labeled them "A" and "B", and for the last 4 years I've never head any problems.