Email Filtering Security: Why It’s An Essential Feature In Enterprise Security

Email filtering is the process of scanning and categorizing an enterprise’s inbound and outbound email traffic. It includes segregating emails containing spam, bulk, adult content, virus, etc., thus ensuring that only the safe ones pass to the inbox of the user. The security accorded by the process to emails is what we call as email filtering security.

While inbound email filtering involves scanning of emails directed to a user’s address, outbound email filtering removes potentially harmful content or malware from outgoing emails. Organizations deploy outbound email filter apps to prevent leakage of confidential user/organizational data.

An email security service uses email filtering solution that detects and deletes hostile content at preliminary SMTP connection stage. It tags emails and quarantines inbound/outbound emails for further checking.

enterprise spam filter

Reasons For Using Email Filtering Services

Spammers use phishing to steal confidential data and use it for illegal purposes. Phishing is a fraudulent attempt implemented through emails. Phishers send bulk emails to users (they may even choose C-suite employees, known as ‘Whales’) with fake URLs embedded. These links, when clicked, land the user on a web page and ask for immediate actions such as to enter personal/professional credentials. These are further used for illegal purposes or making money. These emails include:

  • Malicious URLs, if clicked, redirect to hacker’s webpage and trap the users to release their information like bank details, Social Security numbers, etc.
  • Attachments containing Trojans, ransomware, and other malware threats.

An efficient email filtering service uses advanced technologies to detect and categorize these spam emails so that the users do not fall prey to the malicious acts.

Basic Operating Procedure Of Email Filter Apps

In the email sending process, a mail transfer agent (MTA)/MX host/ Mail Transfer Server is software that transfers emails from one computer to another using SMTP. Email service providers install mail filters in their respective MTAs. These mail filters may include anti-spam filters, authentication verification, anti-virus check, and URL filtering.

An email filtering solution offers customizable email filtering criteria to their clients. Users may set up manual filters that can fetch data according to the filter criteria set up.

Filters use machine learning for decision making by matching the regular patterns of a user. Keyword matching is also used as a mail filter technique, in which a filter looks for matching keywords in the message body and sender’s email address. Procmail is a data-driven programming language (data matching rather than code sequence following), and filter software uses Procmail for complex control flow and logic.

Alternatively, filters may use Document Classification Technique such as Naïve Bayes Classifier to classify the documents (attributes are: Image, Text, Music, Subject, etc.) and, based on that, make filtering decisions.

email spam service
email spam filtering service

Some Email Filtering Tool Types:

Bayesian Filtering

This email filtering tool approach uses text classification and correlates the keywords or token in the email body text, subject line, the sender’s address. It calculates the probability to detect spam emails.


This method maintains a list of trusted sender’s email addresses, and these pass without a check.


Received spam emails addresses are data-based, and future emails from these addresses are blocked and filtered out to spam folder or deleted.

Email filtering security service involves low overall management and time commitment for protecting an organization/individual from hacker’s sophisticated phishing attempts. Enterprise spam filter reviews and ratings rank these providers and their services to help you choose better.

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