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 [http://en.wikipedia.org/wiki/False_positive#False_positive_error 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://en.wikipedia.org/wiki/DNSBL URIBLs and RBLs]: internal, [http://dnsbl.invaluement.com/ Invaluement], [http://sorbs.net SORBS], [http://www.gbudb.com/truncate/ GBUDB], [http://wl.org.za/ Whitelist ZA]
  
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- RFC complaint: Imaginet enforces email addresses, headers, IP addresses, sending SMTP server to be RFC compliance.
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- Virus and [http://sanesecurity.com/ spam] filtering with [http://www.clamav.net/lang/en/ ClamAV]
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- Manual database maintained internally from reported email addresses from our customers.  
 
  
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- Checks mail for blacklisted links within the body of the message.  
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- Checking of mail against a 'fuzzy' checksum database generated from mail received by [http://en.wikipedia.org/wiki/Spamtrap spamtraps]
  
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- Virus scanned through Clam Antivirus engine.  
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- [http://osbf-lua.luaforge.net/papers/osbf-eddc.pdf Advanced bayesian statistics]
  
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- IP Blacklisting
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- Global and [https://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]
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Spam-filtered mail is delivered to a [[Spam Quarantine]] or, if there is enough of a consensus between the systems we employ, discarded.
  
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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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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 you are still receiving spam you are welcome to forward the spam to abuse@imaginet.co.za.
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[[How you can prevent spam]]
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[[How you can blacklist email addresses]]
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[[What does Imaginet consider spam abuse]]
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[[How to report spam to Imaginet]]

Latest revision as of 14:25, 14 August 2014

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

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

- Virus and spam filtering with ClamAV

- Checking of mail against a 'fuzzy' checksum database generated from mail received by spamtraps

- Advanced bayesian statistics

- Global and customer-operated address blacklists & whitelists

- Strict enforcement of SPF

Spam-filtered mail is delivered to a Spam Quarantine or, if there is enough of a consensus between the systems we employ, discarded.

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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