I guess sending some dollars in an envelope isn't recommended...?
That's what people say... but I have done it many times and never had the slightest problem.
The only advantage to sending a money order is that way you have proof that the recipient received it. If there is trust on both sides of the transaction, then why bother? I mean, the post office is handling millions (maybe even billions?) of letters and parcels every day. They do *not* have time to examine each letter in the hope that there might be cash in it that they can steal!
tanstaafl.