Cisco Cisco Email Security Appliance C160 Mode D'Emploi

Entering a number of invalid recipients per hour enables DHAP for that mail flow policy. By default, 25 
invalid recipients per hour are allowed for public listeners. For private listeners, the maximum invalid 
recipients per hour is unlimited by default. Setting it to “Unlimited” means that DHAP is not enabled 
for that mail flow policy.

AsyncOS provides support for SMTP authentication. SMTP Auth is a mechanism for authenticating 
clients connected to an SMTP server.

The practical use of this mechanism is that users at a given organization are able to send mail using that 
entity’s mail servers even if they are connecting remotely (e.g. from home or while traveling). Mail User 
Agents (MUAs) can issue an authentication request (challenge/response) when attempting to send a 
piece of mail.

Users can also use SMTP authentication for outgoing mail relays. This allows the appliance to make a 
secure connection to a relay server in configurations where the appliance is not at the edge of the 
network.

AsyncOS supports two methods to authenticate user credentials:

You can use an LDAP directory.

You can use a different SMTP server (SMTP Auth forwarding and SMTP Auth outgoing).

Configured SMTP Authentication methods are then used to create SMTP Auth profiles via the 

smtpauthconfig

 command for use within HAT mail flow policies (see