User`s guide

3.5 Antispam control of the SMTP server
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3. Set Max. number of unknown recipients to 10.
4. In Do not apply these limits to IP address group, set Local clients. This will exclude
Kerio Connect users from these rules. If you use private IP addresses in your internal
network, you can simply choose Local Clients group where all private IP addresses ranges
are defined.
Details on security of the SMTP server can be found in chapter SMTP server of the Kerio Con-
nect 7, Administrator’s Guide.
3.5 Antispam control of the SMTP server
The SMTP server is accessible from the Internet and, therefore, it is necessary to configure
an antispam control of the SMTP server. Antispam filters can be set under Configuration →
Content Filtering → Spam Filter:
1. Antispam rating can be started and set on the Spam Rating tab. Default settings of this
tab can be kept.
2. On the Blacklists tab, it is recommended to enable control involving Internet spammer
databases and to set +2 points as a score for each database.
3. Switch to the SpamAssassin tab and enable option Check every incoming message in Spam
URI Realtime Blocklist (SURBL) database.
4. On tabs Caller ID and SPF, set control of e-mail policy records of the sender SMTP server
and set the spam score to +2 points. This control allows to filter out messages with fake
sender addresses.
5. On the Spammer Repellent tab, enable SMTP connection delay (keep the predefined value
of 25 secons). This filter efficiently stops spam messages at the SMTP level which relieves
the server from a remarkable volume of spam testing.
Antispam filters of the SMTP server are focused in the Kerio Connect 7, Administrator’s Guide,
chapter Antispam control of the SMTP server.
3.6 Antivirus control
Another necessary settings of Kerio Connect to be done are enabling of the antivirus control
and attachment filter that can be performed in the following sections: