address verification without SMTP dialog?

[Burkhard Schultheis]

We have made a test of an email verification. It tested 3 addresses
against our domain, the results were OK (existing and not existing). But
in the logs of our mailserver (we have only one!) we cannot find
anything from the test. In these logs you can see all SMTP dialogs but
not the content of the emails. How is it possible to validate an email
address without a SMTP dialog with HELO or EHLO and so on?

Any idea?

Thanks in advance!

Regards
Burkhard