well, mikebw wrote "mail carrier".
I'd assume that it was meant to point towards the people who separate, direct and transport mail inside the postal offices. (this is not meat to be any kind of negative feedback on what mikebw wrote)
Funny thing is, being an actual postman, talking to people, go from house to house delivering mail, is actually a good job for an aspie, being that i'm an undiagnosed aspie (2 psychologists told me "off the record" i might have asperger's, 2 friends that have been diagnosed also told me and 7 other people as well) i know 2 aspies that are postmans, and have been one myself.
One does not have to "really" get involved with people, the only thing you'd have to overcome "if applicable" is the possible shyness that many people have of being judged by their looks, I got fired twice before for "anti-social" behavior but as a postman people have some degree of respect for you and while one meets lots and lots of different people, some will talk to you or try and be friends, and you can talk to them or not (well the "good day" is usually a must), the point is, you can say hi and be on your way, there's no explaining to do, there's no crap (mind the expression) you have to put up with.
Being a postman is usually said to be one of the most stressing jobs ever. (the expression "Going Postal" came from there, also a couple of movies and even Postal the game)
But after being through the experience i'd say that one of us doesn't feel it as much, probably because of the lack of empathy, i personally find it hard to get stressed with things common people would stress about, but get stressed with things people do not stress about, kind of reversed roles.
Anyways, sorry if i didn't give you any solution, just a slight insight, meaning that a job that you'd think has lots of people relations on it, sometimes hasn't.