Common Spam control measures at client's mails gateways

This page contains the common spam control measures which are implemented at
most the client sites.

Please see the client specific page of the details of spam control measure here [1]
and use this page as reference. Because it is not necessary that all features are
implemented at all client mailgateways.

1. SpamAssassin:

   Here we can whitelist/blacklist the specific email-id/Domain of
   sender/recipient.

2. sa-update:

   Sa-update is running on all the server. It is updating the SA definations
   from following channels:

   72_sare_redirect_post3.0.0.cf.sare.sa-update.dostech.net
   70_sare_evilnum0.cf.sare.sa-update.dostech.net
   70_sare_bayes_poison_nxm.cf.sare.sa-update.dostech.net
   70_sare_html0.cf.sare.sa-update.dostech.net
   70_sare_html_eng.cf.sare.sa-update.dostech.net
   70_sare_header0.cf.sare.sa-update.dostech.net
   70_sare_header_eng.cf.sare.sa-update.dostech.net
   70_sare_specific.cf.sare.sa-update.dostech.net
   70_sare_adult.cf.sare.sa-update.dostech.net
   72_sare_bml_post25x.cf.sare.sa-update.dostech.net
   99_sare_fraud_post25x.cf.sare.sa-update.dostech.net
   70_sare_spoof.cf.sare.sa-update.dostech.net
   70_sare_random.cf.sare.sa-update.dostech.net
   70_sare_oem.cf.sare.sa-update.dostech.net
   70_sare_genlsubj0.cf.sare.sa-update.dostech.net
   70_sare_genlsubj_eng.cf.sare.sa-update.dostech.net
   70_sare_unsub.cf.sare.sa-update.dostech.net
   70_sare_uri0.cf.sare.sa-update.dostech.net
   70_sare_obfu0.cf.sare.sa-update.dostech.net
   70_sare_stocks.cf.sare.sa-update.dostech.net
   saupdates.openprotect.com
   updates.spamassassin.org

   The above channels are used at all the locations to update SA definitions.

3. Sendmail DNSBL:

   Following is the list of DNS blacklisting data base used at most sites:

   bl.spamcop.net
   zen.spamhaus.org
   list.dsbl.org

4. Greylisting:

   Greylisting rejects the unique IP, sender, recipients pair for 1 minute,
   when it sees the unique triplet of these three the first time. If this
   triplet is seen again within 5 days the triplet is automatically
   whitelisted for 60 days. The whitelisted IP/sender/recipient or triplet
   are not delayed.

   We have white listed the following IPs explicitly apart from the list of
   IPs that come with default configuration of greylisting:

   list gmail of gmail IP addresses
   66.249.82.0/24
   64.233.162.0/24
   64.233.170.0/24
   64.233.182.0/24
   64.233.184.0/24
   72.14.204.0/24
   216.239.56.0/24

   list yahoo IP addresses
   66.94.237.0/24
   66.218.66.0/24
   66.218.67.0/24
   66.218.69.0/24
   216.136.226.0/24

   The above Yahoo and Gmail IPs are whitelisted on all the servers where
   greylisting is enabled.

5. Greet Pause:

   The pause before SMTP greeting is set to 3 seconds at all the sites
   where greet pause feature is enabled.

   The Greet Pause for localhost(127) is set to zero, as locally generated
   mails should not be delayed.