disable SENDER checking private authorized senders

Which domains are checked by chkuser?

chkuser handles all domains who are in rcpthosts (or morercpthosts) and inside virtualdomains.

If the domain is only inside rcpthosts (or morercpthosts), no checking is done.

So, if you are a backup MX domains, and want just to accept messages for some domains without checking any recipient, be sure your domain is in rcpthosts but not in virtualhosts (and create an entry in smtproutes if you need so).

How to disable SENDER checking for my private authorized senders?

Enable (uncomment) the following define, and set it to RELAYCLIENT.

#define CHKUSER_SENDER_NOCHECK_VARIABLE "RELAYCLIENT"

Thanks to Alex Pleiner for this tip.