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A complete email address (e.g. [email protected])
Emails from this sender will be rejected. Note that the so called "envelope from"
will be compared here and not the from header which is usually displayed by mail
client programs.
A Domain (e.g. example.com)
In this case SX-GATE won't accept emails from any sender within this
domain and subdomains. For example emails from [email protected] and
[email protected] would be denied.
Besides checking the email address, SX-GATE will lookup the IP address of
the SMTP connections source in the DNS. If the hostname is within the blocked
domain, the mail won't be accepted either. Let's assume the connection source is
the IP 169.254.254.20 and DNS reveals that this IP corresponds to the hostname
254-20.ppp-pool.example.com. In this case the mail would be blocked as well.
An IP address
Emails will be blocked if the source IP of the SMTP connection is listed here.
In the maillog of SX-GATE the "envelop from" and the source
IP of every email is logged. Search in the log for the line which
contains the source information of an email ("from="). "from="
provides the "envelope from"and the source IP of the SMTP
connection is listed as "relay=".
For emails which have been retrieved from a POP server by the
SX-GATE mail client, the source IP of the connection is always
SX-GATE itself (127.0.0.1, localhost). Therefore you can only
deny emails based on the "envelope from".
14.5.2-F
Resource limits
On this tab you can configure various limits which help to protect SX-GATE and
downstream systems from being overloaded. The restrictions apply to all SMTP
connections accepted by SX-GATE. It does not matter if a mail client program or
an other mail server establishes the connection. Usually all restrictions apply already
before the actual email contents are transmitted.
Maximum number of concurrent connections
This setting limits the total number of incoming connections. This includes connections
from internal LAN workstations as well as connections originating somewhere in the
Internet. The limit is meant to protect SX-GATE from overload conditions.
