Sendmail local error code

[Account for Debian group mail <debian@pcez.com>]

Hello,

I'm getting an error code on an outgoing mail server I have not seen 
before. The system is using a sendmail ver 8.3.

It's telling me:

MDeferred: 451 Requested action aborted: local error in processing (code: 11)

Anyone seen this one before? I've done some looking on the web but could 
not find anything about a code: 11

Thanks,

Ken