Email:Filtering
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Virus Scanning
At Saskaweb.com we employ incoming and outgoing virus scanning on all accounts unless 'No Processing' has been set on the [Email:Administration|admin] page. As of October 1st, 2007 our virus scanner has signatures for over 157 000 malware objects. Client accounts that are sending virus infected messages will be automatically notified.
Nonetheless, we strongly recommend that client computers be equipped with an antivirus program capable of scanning email. Domain spamfilter customers running Microsoft Exchange should use appropriate Exchange antivirus software. As has been repeatedly demonstrated, current antivirus software is essential for Microsoft Windows systems.
Remember: saskaweb.com is NOT liable if you receive something nasty! You have been warned :)
Spam Filtering Techniques
At Saskaweb.com we employ numerous methods of spam filtering.
- Whitelisting
- Whitelisting is a technique used to ensure your legitimate email gets through. When you send an email through our servers, the recipient address is automatically added to a whitelist. In addition, an address can be manually added to the whitelist by forwarding a mail from the address to be whitelisted to whitelist@spamcontrol.local.
- Whitelisted addresses are given a pass through most of the spam filtering techniques. Thus the easiest way to ensure an email gets through the spam filter is to first send that person an email.
- If there are any domains that only send you legitimate and important email, please notify support@saskaweb.com so that we can add the entire domain to your whitelist.
- Blacklisting
- Blacklisting is used to block a specific email address or domain. Blacklisting is not very useful in today's fight against spammers as most spam forges the 'From' field to a variety of different email addresses. Nevertheless, blacklisting domains and addresses can still be of use to block pesky senders.
- Bayesian filtering
- Bayesian filtering recognizes words and word combinations to determine if a message is spam or not. After a considerable learning process, a bayesian filter becomes quite effective in eliminating spam. We encourage our clients to help improve our Bayesian filter by forwarding spam messages that have gotten through to reportspam@spamcontrol.local. In addition, messages that were incorrectly labelled spam should be forwarded to notspam@spamcontrol.local
- Realtime Blacklists
- Realtime Blacklists (RBLs) are useful in blocking virus infected computers or open relays on mail servers. We have found that RBLs have to be used carefully as RBLs make mistakes, viruses are cleared, and misbehaving mail servers can be fixed. For these reasons, a message has to be found on multiple RBLs for our servers to block it. By default, messages failing an RBL check are dropped. You can request that you receive RBL failing messages in your junk email by requesting it from support@saskaweb.com
- Sender Policy Framework
- SPF is an excellent method of blocking messages with forged 'From' fields. The biggest weakness to SPF is that it is not universally used. We publish restrictive records for all domains that we host and encourage others to do the same. With most domains not using SPF, however, we can not deny messages from domains lacking SPF records.
- DNS methods
- We demand that all incoming messages come from IPs that have properly published PTR records.
Attachment Blocking
We have two criteria for attachment blocking on incoming email:
- Whitelisted addresses
- The following attachments are always disallowed: exe, scr, pif, vbe, vbs, js, jse, wsh, wsf, shs, shb, lnk, bat, cmd, com, hta, and htb
- Non whitelisted addresses
- Only attachments with the following extensions are passed: doc,xls,ppt,pdf,zip,rtf,txt,jpg,png,jpeg, and bmp
If your domain requires additional attachments from non-whitelisted addresses, please make a request to support@saskaweb.com. Otherwise, the easiest way to ensure your attachment gets through is to add them to the whitelist by simply sending them an email
