If your address isn't in the postal database you should fill out that form and contact them. Your second step should be to call your local postmaster and figure

If your address isn't in the postal database you should fill out that form and contact them. Your second step should be to call your local postmaster and figure out what is going on. It is possible your landlord didn't know any better and just told you to use an apartment number. Having an entry on a support contact dropdown simply means they want to route those requests differently than general support questions. It does not indicate that the problem is widespread.