Cisco Cisco Email Security Appliance C160 Mode D'Emploi

If you enable this feature, message delivery will not be reliable and may lead to loss of messages. Also, 
your appliance will not be RFC 5321-compliant. For more information, see 

.

When the Possible Delivery feature is enabled, AsyncOS treats any message that times-out after the body 
of the message is delivered, but before recipient host acknowledges receipt of the message, as a “possible 
delivery.” This functionality prevents recipients from receiving multiple copies of a message if 
continuous errors at their recipient host prevent acknowledgment of receipt. AsyncOS logs this recipient 
as a possible delivery in the mail logs and counts the message as completed.

You also specify the default maximum number of concurrent connections the appliance makes for 
outbound message delivery. (The system-wide default is 10,000 connections to separate domains.) The 
limit is monitored in conjunction with the per-listener maximum outbound message delivery 
concurrency (the default per listener is 600 connections for private listeners and 1000 connections for 
public listeners). Setting the value lower than the default prevents the gateway from dominating weaker 
networks. For example, certain firewalls do not support large numbers of connections, and this could 
induce Denial of Service (DoS) warnings in these environments. 

In the following example, the 

deliveryconfig

 command is used to set the default interface to “Auto” 

with “Possible Delivery” enabled. The system-wide maximum outbound message delivery is set to 9000 
connections. 

mail3.example.com> deliveryconfig

Choose the operation you want to perform:

- SETUP - Configure mail delivery.

[]> setup

Choose the default interface to deliver mail.

1. Auto

2. PublicNet2 (192.168.3.1/24: mail4.example.com)

3. Management (192.168.42.42/24: mail3.example.com)

4. PrivateNet (192.168.1.1/24: mail3.example.com)