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< Technology

Email Filtering Architecture

How we ensure confidence in our client’s email

Want to learn more about how we filter emails? You’ve come to the right place. Hold on to your hats: this might get technical.

An email that could create chaos.

Most users can't tell a good email from a bad one. How confident are you?

See how we filter your emails to keep you safe.

Prefiltering

This initial filtering step happens while we are in the process of receiving emails. Analyzing the sender’s behaviour during this step allows us to reject the worst offenders. The checks that are run at this stage are relatively standard, meaning that the risk of false positives is quite low. Any messages blocked at this stage are immediately returned to the sender with a descriptive error message. If the sender is legitimate, they will know what to do to correct the issue.

2 - Envelope Filtering ENG

Content Scan

This is where the most complex verifications happen. There are four major types of verifications being performed simultaneously: ZeroScan, ZeroMalware, ZeroPhishing and ZeroPhishing Advanced.

3 - Content Filtering ENG

Send to server

Once all checks are complete, emails are placed in the outbound queue and routed to the clients’ mail servers. Our filters constantly monitor client servers for availability. If for some reason, the remote server is unable to receive emails, we will retain all messages for up to five days.

4 - Output ENG

An email you can trust.

The end result: you have the confidence to open any email you receive.

ZeroSPAM Rocks!

Read the full review here

Chris S.

ZeroPrefilter alpha

The Prefilter – Checking the Basics

Our filters start the scanning process during the SMTP connection. Even before we've seen the email content or subject, our filters can already split the good from the bad by analyzing how the sending server is communicating. Bad emails are blocked before they even reach the quarantine, making your life easier.

Throttling

  • Protects against DDOS and mail floods

Standards compliance

  • Checks that messages respect the basics of email-sending
  • Rejects emails that fail RFC compliance

Blacklisting

  • Check reputable external blacklists
  • Client preferences applied to reduce quarantine size
ZeroScan alpha

Safe Content

Our filters are thorough and check every part of the email content: subject, content, URLs, images, etc. Some of the analysis is done with our manmade rules; over 10,000 of them! Some of the analysis is done with our Machine Learning engine called Tyr. All blocked emails are placed in quarantine with a score so you can see just how bad they are.

Link scanning

  • URIBL and heuristic analysis
  • Rapid analysis of links. No delays in receiving emails

Content filtering - heuristics

  • Over 10k rules built and refined over the years
  • Curated daily by dedicated experts

Content filtering - AI

  • Machine-learning recognizes and classifies emails
  • In-house research team
ZeroMalware alpha

Safe Attachments

Who likes malware? Not us! Our filters check all attached files to block potential infections. To protect against Zero-Days, our filters will automatically quarantine messages that have potentially dangerous files like executables or Office documents with Macros. Blocked messages are placed in quarantine so they can be easily released if needed.

Antivirus

  • Detects known viruses
  • Identifies phishing indicators
  • Powered by Bit Defender and ClamAV

File-type blocking

  • Pre-configured for optimal security
  • Blocks executable files, dangerous Office documents, and zip bombs
  • Fully customizable
  • 0-day protection
ZeroPhishing alpha

Basic anti-phishing

We're working very hard so you don't have to. Scammers are always coming up with new ways to make their emails look legit. ZeroPhishing is there to make sure that spoofed emails are blocked. Our filters are updated daily so you don't have to worry about opening your emails.

Content filtering - heuristics

  • Part of the 10k rules dedicated to phishing
  • Updated every day based on customer feedback

Email authentication (SPF / DKIM / DMARC)

  • In line with industry best-practices
  • Backed by an experienced team that specializes in troubleshooting
ZeroPhishing Advanced alpha

Advanced Anti-phishing

Everyone gets advanced protection against threats like BEC and CEO Scams at no extra cost. While this filtering might be advanced, it sure is easy to set up and use.

Spearphishing module

  • Definitive and simple solution to BEC and CEO scams
  • Flexible and powerful protection

Lexicographical analysis

  • Protects against lookalike domain spoofs
  • Applied automatically to all emails
Now that you know how the filtering works, how about trying it out?

The Importance of SMTP Authentication Verifications

SPF, DKIM, and DMARC keeping you safe

While these authentication frameworks have existed for many years, not everyone enforces them. We do.
We don’t just use them, we know how they work. Want help setting up authentication verifications? We’ve got you covered. These are, after all, important protections. We have years of experience setting up and troubleshooting DNS entries. It’s the kind of thing we email geeks find interesting.