Cisco Cisco Content Security Management Appliance M390 ユーザーガイド
Chapter 10 Configuring SMTP Routing
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Cisco IronPort AsyncOS 7.2.0 for Security Management User Guide
OL-21768-01
Note
If you have completed the System Setup Wizard in the GUI and committed the
changes, you defined the first SMTP route entries on the appliance for each RAT
entry you entered at that time.
changes, you defined the first SMTP route entries on the appliance for each RAT
entry you entered at that time.
SMTP Routes Overview
SMTP Routes allow you to redirect all email for a particular domain to a different
mail exchange (MX) host. For example, you could make a mapping from
mail exchange (MX) host. For example, you could make a mapping from
example.com
to
groupware.example.com
. This mapping causes any email with
@example.com
in the Envelope Recipient address to go instead to
groupware.example.com
. The system performs an “MX” lookup on
groupware.example.com
, and then performs an “A” lookup on the host,
just like
a normal email delivery. This alternate MX host does not need to be listed in DNS
MX records and it does not even need to be a member of the domain whose email
is being redirected. The Cisco IronPort AsyncOS operating system allows up to
ten thousand (10,000) SMTP Route mappings to be configured for your Cisco
IronPort appliance. (See
MX records and it does not even need to be a member of the domain whose email
is being redirected. The Cisco IronPort AsyncOS operating system allows up to
ten thousand (10,000) SMTP Route mappings to be configured for your Cisco
IronPort appliance. (See
This feature also allows host “globbing.” If you specify a partial domain, such as
example.com
, then any domain ending in
example.com
matches the entry. For
instance,
fred@foo.example.com
and
wilma@bar.example.com
both match the
mapping.
If a host is not found in the SMTP Routes table, an MX lookup is performed using
DNS. The result is not re-checked against the SMTP Routes table. If the DNS MX
entry for
DNS. The result is not re-checked against the SMTP Routes table. If the DNS MX
entry for
foo.domain
is
bar.domain
, any email sent to
foo.domain
is delivered to
the host
bar.domain
. If you create a mapping for
bar.domain
to some other host,
email addressed to
foo.domain
is not affected.
In other words, recursive entries are not followed. If there is an entry for
a.domain
to redirect to
b.domain
, and a subsequent entry to redirect email for
b.domain
to
a.domain
, a mail loop will not be created. In this case, email addressed to
a.domain
will be delivered to the MX host specified by
b.domain
, and conversely
email addressed to
b.domain
will be delivered to the MX host specified by
a.domain
.
The SMTP Routes table is read from the top down for every email delivery. The
most specific entry that matches a mapping wins. For example, if there are
mappings for both
most specific entry that matches a mapping wins. For example, if there are
mappings for both
host1.example.com
and
example.com
in the SMTP Routes