Code Blue TOOLVOX X3 - Manual (Page 126)

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ToolVox® X3
Administrator Guide
SMTP server response on invalid hostname reject, SMTP server response on unknown domain
reject, SMTP server response on unknown hostname reject
These options configure the error result code that will be sent to the client when any of the specified
restrictions are applied. These errors have sensible default values and generally should not need to
be changed. Consult with RFC 822 if you wish to understand more about the SMTP error codes or
have a reason to change any of these values.
SMTP Client Options
The SMTP client options configures how Postfix will behave when dealing with other mail servers
as a client, i.e., when sending mail on behalf of a user. This portion of the configuration primarily
dictates how the server will respond to certain error conditions.
Action when listed as best MX server
As discussed in the BIND chapter, a mail server performs a name server query to find the MX, or
mail server, record for the destination domain. If this record indicates that the local server is the
server to which mail should be sent, it can respond in a couple of ways. The default is to bounce the
message with an error indicating a mail loop. If the field is selected and local is entered, the mail will
be directed to the local delivery agent instead of bouncing. This option correlates to the best_mx_
transport directive.
Hosts/domains to hand off mail to on invalid destination
By default, mail that cannot be delivered because the destination is invalid will be bounced with an
appropriate error message. However, it is possible to configure Postfix to hand off email to another
server instead. This option correlates to the fallback_relay directive.
Ignore MX lookup error
If a name server query fails to provide an MX record, the server defaults to deferring the mail and
trying again later. If Yes is selected, an A record query will be done and an attempt to deliver to the
resulting address will be made. This option correlates to the ignore_mx_lookup_error directive.
Skip 4xx greeting
If a remote server responds to a connection with a 4XX status code, Postfix will, by default, select
the next available mail exchanger specified by the MX records. If set to No, mail delivery will be
deferred after the first mail delivery attempt and another attempt will be made later. This option
correlates to the smtp_skip_4xx_greeting directive.
Skip wait for the QUIT command
This option configures whether Postfix will wait for the receiving mail server to respond to the QUIT
command. This option correlates to the smtp_skip_quit_response directive and defaults to no.
Max number of parallel deliveries to the same destination
This option specifies the maximum number of deliveries that Postfix will perform to the same
destination simultaneously. This option correlates to the smtp_destination_concurrency_limit
directive and defaults to the system-wide limit for parellel deliveries configured in the Delivery