postfix overrides status code from 5.1.1 to 5.1.7?

[Mayuresh <mayuresh%acm.org@localhost>]

I have a postfix recipe to protect recipients which rejects a message if
the senders are outside allowable set with a code of 550 5.1.1

But the sender receives the code as 5.1.7.

I see the postfix log showing the following line:

  mapping DSN status 5.1.1 into Sender address status 5.1.7


About 6 months back I had tested these recipes and they were working fine
(on a different system, may be NetBSD 8.0_RC1 that time).

Any idea why postfix is mapping the status this way?

It does not matter greatly, but if the rejected mail was from gmail, it
tells the sender that the `server is misconfigured' if it gets 5.1.7.
Instead if it receives 5.1.1 it just says no such user.

Mayuresh