PostPosted: Wed Feb 01, 2006 12:46 am Post subject:
Can be " Another's " as well, in certain contexts.
Could even be foreigner's or alien's, in the right context.

I would agree with the translations that kwatts provided, with three slight alterations -- the literal translation would be "letters" but I think if a native speaker were to say it they would use "mail/почта" instead. No big deal -- the meaning remains, but it just sounds a bit more natural to me. I think strictly speaker, grammar demands that you say "someone's" and not "somebody's"? You might also consider revising the word order by saying "It is improper to read someone else's mail"