[vchkpw] limit domain

[José Antonio García]

Hi

I would like to know how limit one domain (domain.com) so that the
accounts  of that domain can´t send email between them.

For instance:

[EMAIL PROTECTED] and [EMAIL PROTECTED] can´t send email between them

I have qmail1.03, vpopmail 5.2.1, qmail-scanner-1.22.

Thanks