If specified, DeleGate verifies (using the SMTP protocol) the validity
of E-mail address given by anonymous users.
In HTTP-DeleGate, the E-mail address must be given as Username
part in Authorization.
In FTP-Delegate, it must be given as a password for the anonymous
With this AUTH, invalid E-mail addresses can be rejected.
When the address is valid but is in a format like "user@host",
it will be expanded automatically to a FQDN format like
If the third field is "-" (i.e. AUTH="anonftp:smtp-vrfy:-@*")
only the connectivity to mail server at "host.domain" is checked.