Spam filtering Solution
Spam e-mail is a real problem. Not only does it clutter up your inbox, but it will be costing your business a fairly large, but intangible amount of money.
It is estimated that spam e-mail messages account for 80% or more of all e-mail traffic.
Ingenious can provide a little known and extremely effective server based anti-spam solution. We have been investigating this subject for several years and can offer a simple program that sits on your server and rejects spam before it enters your organisation's network taking up Internet bandwidth and server disk space
We have had experience with ISP based anti-spam solutions, expensive bespoke solutions such as Barracuda, and can find nothing in the same price range that matches the software for effectiveness and price (typically about £110-£120 per server, unlimited users, depending on exchange rate fluctuations).
Product details:
The software is called ORF Enterprise Edition and is an anti-spam solution that helps you to block spam before it reaches your network. ORF uses a combination of anti-spam technologies and custom filtering options to stop the spam on SMTP protocol level. ORF can be used with the IIS SMTP Service shipped with Microsoft Windows 2000/2003 Servers and Microsoft Exchange 2000/2003 Servers.
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The techie stuff:
All tests that can test before arrival as well as on arrival will be set to do both. This is to combat mail arriving from the intermediate host (your ISP's mail relay server - mail may be set to go here if your server is temporarily unavailable and is then be forwarded - check your MX records if you are unsure); mail from intermediate hosts can only be tested on arrival.
The following summarises how the software could be configured and details each of the 19 different tests available:
DNS Whitelist - Bonded Sender Program, enabled, before and on arrival. See http://www.bondedsender.org
DNS Blacklists, enabled, before and on arrival. Amongst others (18 to choose from); SpamCop http://www.spamcop.net, Spamhaus SBL (Spam Block List) http://www.spamhaus.org, Not Just Another Bogus List (NJABL Combined List) http://www.njabl.org, CBL Composite Blocking List http://www.cbl.abuseat.org/. These are on-line databases of known Spam sources.
Reverse DNS, enabled, before and on arrival. The sender's domain must have a DNS MX or A record.
HELO blacklist, enabled, before and on arrival. Blacklist e-mail if the domain specified by the sender is malformed, or the same as the recipient domain. Can also be set to block mail if the domain is not a fully qualified domain name.
SPF Test, enabled, before and on arrival. Blocks those explicitly denied. Can be set to blacklist on SPF SoftFail. See http://www.openspf.org/
IP Whitelist, enabled by default. Can be populated as needed.
Sender Whitelist, enabled by default. Can be populated as needed.
Recipient Whitelist, enabled by default. Can be populated as needed.
Auto Sender Whitelist, enabled, before and on arrival. Records can be set for up to a 6 month lifetime (maximum - database size to be checked regularly and this reduced if it grows too large). IP exceptions can be added. All outgoing mail end recipients are added automatically so that any future e-mails from these recipients will not be tested. This is very useful as a quick fix in the vary rare occasion that someone is being blocked by the software - simply e-mail them.
IP Blacklist, enabled, before and on arrival. Can be populated as needed.
Sender Blacklist, enabled, before and on arrival. Can be populated as needed.
Recipient Blacklist, enabled, before and on arrival. Can be populated as needed.
Active Directory, enabled, before and on arrival. Set to synchronise with AD (the internal user and e-mail account database) every 15 mins.
Tarpit Delay, enabled, before and on arrival. Set for AD or Recipient Blacklist only - can be set for all blacklists. Delays responses to sender's server for 60 seconds. Slows down Directory Harvest Attacks (DHA's) - this is where a spammer sends e-mails to made-up names to see which ones don't get rejected.
Greylisting, not enabled. Rejects unknown senders for 60 seconds. Sender, Recipient, and IP exceptions can be listed. Works on a combination of the sending server IP address, the sender e-mail address, and the recipient address. Good self-learning test, but delays e-mails for 15 mins or more. Record lifetime can be set. Typically results in mail passing on to secondary MX record and then bypassing tests as the relay server is listed as intermediate host, and mail from this server then has to fall back to the 'after arrival' checks. Can be implemented if needed - good test, but delays e-mail - would possibly be a good idea after the Auto-Sender list populates for a while.
Keyword Filtering, enabled, on arrival only. Can be set to filter variations on all the usual profanities etc.
Attachment Filtering, enabled, on arrival only. Set to block all dangerous attachment file types (usually based on Outlook 2003 blocked file types).
URL Domain Blacklist, enabled, on arrival only. Checks URLs and links in message body. Set for all 5 available; AbuseButler spamveritised sites, Combined SURBL list, OutBlaze spamveritised sites, sa-blacklist and other domains, SpamCop message-body URI domains.
External Agents, See http://www.vamsoft.com/agentdefs.asp. Can be set to external AV and anti-Spam agents amongst others.