lucy24 - 3:50 am on Sep 14, 2011 (gmt 0)

What's the problem?

"bleep" seems to sum it up ;)

The sender is not authorized to send to the destination. This can be the result of per-host or per-recipient filtering.

But I like the generic x.7.x explanation better:

The security or policy status codes report failures involving policies such as per-recipient or per-host filtering and cryptographic operations. Security and policy status issues are assumed to be under the control of either or both the sender and recipient. Both the sender and recipient must permit the exchange of messages and arrange the exchange of necessary keys and certificates for cryptographic operations.

In other words, you need to get together with the recipient-- by carrier pigeon, I guess-- and agree on, uhm, something. Seems a bit extreme if all you were trying to say was "Yes, we have that in stock".