Difference between revisions of "How Imaginet blocks spam"

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Imaginet has implemented a combination of spam filter and email rejection methods to firstly protect our systems from unnecessary overload aswell as protect our users from receiving unwanted spam emails. As a matter of interest, we averagely block 80% of all incoming email throughout the year. It is near almost impossible to prevent all unwanted spam due to legitimate email not being received by our customers. Imaginet continuously maintains, updates and investigates our spam systems to make sure it running effectively and efficiently. These are some of the methods and systems we use:  
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Imaginet uses a bespoke spam filtering system aimed at providing the best possible spam filtering with near-zero false-positives. Techniques used include:
  
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- SPF: Sender Policy Framework is an email validation system designed to prevent email spam by detecting email spoofing, a common vulnerability, by verifying sender IP addresses.
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- [http://jessekornblum.com/presentations/cdfsl07.pdf Fuzzy checksums]
  
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- RFC complaint: Imaginet enforces email addresses, headers, IP addresses, sending SMTP server to be RFC compliance.
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- [http://osbf-lua.luaforge.net/papers/osbf-eddc.pdf Advanced bayesian statistics]
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- Manual database maintained internally, containing spam samples reported by our clients.  
 
  
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- Checks mail for blacklisted links within the body of the message.  
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- [http://en.wikipedia.org/wiki/DNSBL URIBLs and RBLs]: internal, [http://sorbs.net SORBS], [http://www.gbudb.com/truncate/ GBUDB], [http://wl.org.za/ Whitelist ZA]
  
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- Virus scanned through Clam Antivirus engine.  
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- Virus filtering with [http://www.clamav.net/lang/en/ ClamAV]
  
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- IP Blacklisting
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- Global and [http://my.imaginet.co.za customer-operated] address blacklists & whitelists
  
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- Imaginet rate limits emails being sent through our smtp servers to 600 an hour or 45 email messages every 10 minutes.
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- Strict enforcement of [http://en.wikipedia.org/wiki/Sender_Policy_Framework SPF]
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- Check manual blacklisting system on [http://my.imaginet.co.za mydot].
 
  
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- RBL's: Real-time Blackhole List (RBL) is a list of IP addresses published through the Internet Domain Name Service (DNS) either as a zone file that can be used by DNS server software, or as a live DNS zone that can be queried in real-time, we download these lists from [http://spamhaus.org Spamhaus],[http://spamcop.net Spamcop], [http://sorbs.net SORBS], [http://www.dnsbl.info DNSBL] and others.
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You can help us improve accuracy by reporting misclassified mail to us, please see [[How to report spam to Imaginet]]
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If the above is not enough we also have a 3rd party Bayesian spam filter that includes [http://spamassassin.apache.org Spam Assassin],Bayesian filters and IP filters.
 
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If you are still receiving spam please read [[How to report spam to Imaginet]]
 
  
 
[[How you can prevent spam]]
 
[[How you can prevent spam]]

Revision as of 13:44, 24 March 2014

Imaginet uses a bespoke spam filtering system aimed at providing the best possible spam filtering with near-zero false-positives. Techniques used include:

- Fuzzy checksums

- Advanced bayesian statistics

- URIBLs and RBLs: internal, SORBS, GBUDB, Whitelist ZA

- Virus filtering with ClamAV

- Global and customer-operated address blacklists & whitelists

- Strict enforcement of SPF

You can help us improve accuracy by reporting misclassified mail to us, please see How to report spam to Imaginet

How you can prevent spam

How you can blacklist email addresses

What does Imaginet consider spam abuse

How to report spam to Imaginet

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