[exim] Wrong enhanced status code

Hi,

I got a message from a user that our exim apparently sends a wrong
status code on full mailboxes.

Something like this:

550 Mailbox is full
550 5.1.1 user@???… User unknown

So on a Mailbox is full a User unknown seems to be returned on a full
mailbox. In my

In my acl I have where I deny messages to full mailboxes the following:

deny  message         = Mailbox is full
       conditions…

a) how can I test this myself? I created a full mailbox but in a simple
telnet-session I get only the 550 Mailbox is full; and not the enhanced
status code
b) how can I configure the correct status code?
c) can me tell someone where in the source this is set? I am greping
through the source code and cannot find anything about RFC 1893, 3463,
5248 or enhanced status codes.

Best,

Niels