In the USA are there (m)any airports that have mail boxes landside? [I think one of their fears is that an explosive device can be deposited--since there is NO landside security.
2 data points.
IIRC, SEA has at least one mailbox landside, right across from a checkpoint.
I was told (when I went looking for one and asked) that there are landside mail boxes at ATL. There supposedly used to be a mailbox airside in the international terminal but it was moved for security reasons.