Cisco Cisco Email Security Appliance X1050 Guía Del Usuario
Chapter 4 Validating Recipients Using an SMTP Server
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Cisco IronPort AsyncOS 7.5 for Email Advanced Configuration Guide
OL-25137-01
Call Ahead Server Responses
The SMTP server may return the following responses:
•
2xx: When an SMTP code starting with 2 is received from the call-ahead
server, the recipient is accepted. For example, a response of 250 allows the
mailing action to continue.
server, the recipient is accepted. For example, a response of 250 allows the
mailing action to continue.
•
4xx: An SMTP code starting with a 4 means that a temporary failure has
occurred in processing the SMTP request. A retry may later be processed
successfully. For example, a response of 451 means the requested action was
aborted or there was a local error in processing.
occurred in processing the SMTP request. A retry may later be processed
successfully. For example, a response of 451 means the requested action was
aborted or there was a local error in processing.
•
5xx: An SMTP code starting with 5 means a permanent failure in processing
the SMTP request occurred. For example, a response of 550 means the
requested action was not taken or the mailbox was unavailable.
the SMTP request occurred. For example, a response of 550 means the
requested action was not taken or the mailbox was unavailable.
•
Timeout. If no response is returned from the call-ahead server, you can
configure how long to attempt to retry before a timeout occurs.
configure how long to attempt to retry before a timeout occurs.
•
Connection error. If a connection to the call-ahead server fails, you can
configure whether to accept or reject a connection for the recipient address.
configure whether to accept or reject a connection for the recipient address.
Max. Recipients per
Session
Session
Maximum number of recipients to be validated in a single
SMTP session.
SMTP session.
Specify between 1 - 25,000 sessions.
Max. Connections
per Server
per Server
Maximum number of connections to a single call-ahead
SMTP server.
SMTP server.
Specify between 1-100 connections.
Cache
Size of the cache for SMTP responses. Specify between
100-1,000,000 entries
100-1,000,000 entries
Cache TTL
Time-to-live value for entries in the cache. This field
defaults to 900 seconds. Specify between 60 - 86400
seconds.
defaults to 900 seconds. Specify between 60 - 86400
seconds.
Table 4-2
SMTP Call-Ahead Server Profile Advanced Settings
Setting
Description