DeadBolt SV is a SPAM Filter based on the concept of Sender Verification, also called Sender Address Verification. The system does not use traditional quarantines, bayesian filters, virus definitions or other methods to try to determine if a message is valid or not. Instead it takes a closed-door approach and only allows email through after a sender proves that they are able to receive and reply to email.
The core of the SPAM Filtering system works like this:
- Someone from outside your mail system sends you a message
- DeadBolt SV intercepts the message and checks to see if it recognizes the FROM address
- If the address is known, it lets the email through normally
- If the address is unknown, it queues the message and stops it from being delivered
- It then sends a message back to the sender asking them to complete a simple verification process
- Once the verification is complete, the original queued email is delivered and the sender is added to a “safe” list and future messages sent from that person will not be intercepted
Other DeadBolt SV features are listed below:
- List of verified and safe senders
- List of banned senders
- List of safe domains
- Recipient discard list
- Detailed logging, statistics and reports
- Revolving authentication codes
- To avoid sending verification requests to forged email addresses, the system checks MX Records, SPF Records and blacklists before sending verification requests
- No false positives
- Simple, fast and very effective sender verification procedure
- Prevents Spam from ever reaching your email server
- Users never see the spam so they don’t need to sort through emails or remember to delete it
- Your system doesn’t have to backup the spam
- Your email server databases don’t get bloated with spam
How does this work? Won’t the spammer just verify himself?
Actually, no. The foundation behind spam is in quantity. One statistic showed that for every one million spam messages sent out, the spammer averaged 7 sales (Yes, 7.) therefore, a spammer must send out millions and millions of messages just to get a handful of sales. There is no way that the spammer could verify himself with enough organizations to make it worthwhile. Assuming that a spammer or aggressive salesperson did verify themselves, an administrator can easily ban that sender.Also, the vast majority of spammers use email domains and email addresses that do not really exist. Therefore, when DeadBolt SV sends them a verification request they do not receive it and cannot verify themselves. If the administrator has MX Checking enabled, DeadBolt SV will detect that the sender has an invalid email domain and will not even attempt to deliver a verification request.