| Technique |
Description |
| Blacklisting of Web sites and Domains |
Barracuda maintain an up-to-date list of the largest and most aggressive known spammers. This list is maintained by both Barracuda Networks and other anti-spam groups.This list is automatically updated on each filter hourly. |
| Message Content Scoring |
This is configured on a per-user basis. Our scanning methods include a scoring system such that emails are scored based on a number of criteria.If a score is above a predefined threshold, then that email is blocked. |
| Checksum Technology |
Barracuda Networks monitor email traffic via the internet and uses checksum technology to keep track of the number of times a particular message has appeared on the internet. If a message has appeared very broadly, it would be categorised as ‘known spam’. Checksums of known spam messages are deployed to our filters to block the unwanted content. |
| Message Authenticity Checking |
Several algorithms are utilised to verify the authenticity of a message. Some of these are simple checks to verify that the from address is authentic.Some are more complex relating to SMTP protocol |
| Blacklists and Whitelists |
Domains, IPs and email addresses can be blocked or whitelisted (allowed through).These lists may be maintained on a per-user or corporate basis. |
| Rate Controls |
Rate controls are utilised to stop DoS (denial of service) attacks as well as dictionary based spam attacks.Rate controls are integrated and automatic in the filters. |
| Bayesian Algorithms |
Bayesian filters are personalised to each user and company.They adapt automatically to changes in spam trends and definitions. To determine the likelihood that an email is spam, these filters use Bayesian analysis to compare the words or phrases in the email in question to the frequency of the same words or phrases in the intended recipient’s previous emails (both legitimate and spam). |
| Spam Fingerprint Checking |
Fingerprinting techniques examine the characteristics, or fingerprint of emails previously identified as spam and use this information to identify the same or similar email, each time one is intercepted. These real time fingerprint checks are continuously updated by Barracuda and provide a very effective method ofidentifying spam. |
| Intent Analysis |
Intent Analysis is used to look at the objective or goal of the email if the objective of the email is to sell something, (such as click a URL), or get the user to take a particular action that is indicative spam, the email will be categorised as spam. |
| ImageSpam |
Powerful ‘Optical Character Recognition’ engines look at spam containing images, and identify the spam content.e.g.stock selections etc.These recognitions are then fingerprinted and made available to our filters as part of our hourly updates from Barracuda Networks. |
| Dual Layer Antivirus |
2 separate antivirus engines examine all attachments for known viruses. Any zip files or other archives are first decompressed, so their contents can be inspected. |
If your email system becomes unavailable for a period of time (e.g. ISP failure etc), the ‘Reclaim’ antispam service will hold the emails on your behalf for up to 48 hours and then deliver your emails safely when your systems become available again. Our engineers can arrange longer than 48 hour mail storage upon request, should you suspect the mail system will be unavailable for longer periods.
