XnetSolutions SX-GATE, Руководство пользователя

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14.5.3 SPAM/Virus/Malware 351
14.5.3 SPAM/Virus/Malware
The configuration options in this menu are structured by topic. You can change between
the different screens by clicking on the tabs at the top.
14.5.3-A Sanity checks.................................................................. 351
14.5.3-B Greylisting........................................................................ 354
14.5.3-C SPF filter......................................................................... 358
14.5.3-D Virusscan......................................................................... 360
14.5.3-E MIME filter....................................................................... 360
14.5.3-F MIME filter rules.............................................................. 363
14.5.3-G MIME filter options.......................................................... 364
14.5.3-H Relay SPAM filter............................................................ 367
14.5.3-I SPAM scores.................................................................... 369
14.5.3-J SPAM modules................................................................ 371
14.5.3-K SPAM settings................................................................. 373
14.5.3-A Sanity checks
The check you can control on this tab are meant to relieve the malware and SPAM
filters by rejecting some unwanted contents beforehand. The tests 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. An email which violates one of these
checks will already be rejected before the actual payload is being transmitted.
Protection against automated mailers
Many SPAM and virus mails are distributed by rather simple routines, trying to deliver as
many emails as possible in a very short time. This protective function makes use of this
fact. Normally a mail server sends a greeting message as soon as a new connection has
been established. The peer waits for the greeting and sends back a greeting message.
When enabling this feature, SX-GATE sends its greeting with a very short delay. If
the client didn't wait for it, but started to send a batch of commands immediately, the
connection is rejected.
This feature will affect connections from external addresses
only. External addresses are all IPs which are not listed below
"Local IP addresses" in menu "Modules > Mail Server > SMTP
settings" on tab "Relay control". So SX-GATE needs to receive
emails directly per SMTP. There won't be any effect if emails are
retrieved from a POP server.