Demystifying Spam Filtering – (Why did that email get blocked?)

Everyone who does business over email has to contend with the problem of sorting the good emails from the bad. Among the many, many legitimate emails we all get each day, there are always those we don’t want to see, be they annoyances like spam advertisements, or serious security threats in the form of ransomware, impersonation scams, and password phishing attempts.

This article will discuss some of the ins and outs of spam filtering; how it works, where its limitations are, and attempt to answer the question of why a legitimate, even important email, might sometimes get blocked from reaching your inbox.

How it works?

Spam filtering is a security function that can be met by a variety of different tools. The most basic type of spam filter is built right into the application used to manage your email like Outlook, and simply sorts emails into a junk folder based on simple rules. This kind of filter is unsophisticated, prone to error, and easy for an enterprising hacker to bypass.

For this reason, most organizations employ a dedicated spam firewall that sits at the perimeter of their network and scans all emails before they even hit the server, to determine if there are any red flags. Sometimes this process can stop a legitimate email from reaching your inbox. The benefits of this exercise however, greatly outweigh the downside. Even though it is frustrating, to miss an email or put in quarantine, you can have peace of mind knowing that your email system is secure.


Triella recommends and supports Mimecast, an enterprise-class security, archiving, and continuity service for email management. Mimecast provides:

  • 100% virus filtering for incoming email messages and outgoing messages
  • 99.5% spam filtering for incoming email messages
  • Impersonation Protection.  Mimecast ensures that email cannot be spoofed by and external recipient.
  • Data loss prevention.   This means that if there is a loss of data from the email system in house then that data can be recovered from Mimecast.
  • Large File Sending – Mimecast is capable of sending and receiving large files in Outlook eliminating the risk of bounce backs from the mail system indicating an email attachment is too large.
  • Real Time Continuity.  If the email system at the firm were ever to go down – even for maintenance – Mimecast will kick in and allow email to continue functioning on mobile devices and through Outlook during the down time.   When the email system comes back up, all mail is synchronized with the original mailbox.  There is never the risk of being down for email ever again in the future.
  • Secure Mail – Send encrypted mail to a recipient.
  • Archiving and Quick Searching – Mimecast will archive all mail sent and received through the server for up to 99 years.  This allows any message to be searched for and located quickly and easily right from Outlook.
  • Disclaimer Management.  All email disclaimers can be managed from a single location providing a consistent message to all recipients.
  • URL Protection.  All URL’s embedded in emails are scanned to be sure they are safe before the user is taken to the URL.

Mimecast can protect you from a variety of attacks and threats such as mass phishing, spear phishing, impersonation attacks, internal email threats and ransomware. Call us now to learn more about the product! 647.426.1004

Sean Kirby is a Help Desk Manager at Triella.  We are a technology consulting company specializing in providing technology audits, planning advice, project management and other CIO-related services to small and medium-sized firms. Sean can be reached at 647.426.1004. For additional articles, go to our blog page. Triella is a VMware Professional Partner, Microsoft Certified Partner, Citrix Solution Advisor – Silver, Dell Preferred Partner, Authorized Worldox Reseller and a Webroot Reseller.

© 2021 by Triella Corp. All rights reserved. Reproduction with credit is permitted.

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