What does the "Possible Delivery" feature do?

Available Languages

Updated:November 10, 2014

Document ID:118601

Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

Question

Answer

Question

What does the "Possible Delivery" feature do?

Answer

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

myesa.local> deliveryconfig

Default interface to deliver mail: Auto
"Possible Delivery": Enabled
Default system wide maximum outbound message delivery
concurrency: 10000
Default system wide TLS maximum outbound message delivery
concurrency: 100


Choose the operation you want to perform:
- SETUP - Configure mail delivery.
[]> setup

Choose the default interface to deliver mail.
1. Auto
2. Management (192.168.0.199/24: myesa.local)
[1]> 

Enable "Possible Delivery" (recommended)? [Y]> 

Please enter the default system wide maximum outbound message
 delivery concurrency.
[10000]> 

Please enter the default system wide TLS maximum outbound message
delivery concurrency.
[100]>

The timeout is a TCP timeout, normally 5 minutes. SMTP will timeout before 4 minutes.

If this feature is disabled, the Email Security Appliance (ESA) will try to resend the message. If the feature is enabled, the message is seen as delivered.