I have an Iranian friend who used to get letters from home. On the 20 anniversary of the hostage take over, the Iranian government issued a set of commemorative stamps for that occasion. My friend got a few letters from home then and those stamps were on the envelopes. One of them is a picture of an American hostage with an American flag rapped over his entire face.
The U.S. Post Office duly delivered the letters without a hitch and without complaints.