Corporate email remains the primary attack vector against organizations: it's where phishing messages, malicious attachments, and fraudulent payment requests arrive. Choosing a protection tool is a strategic decision that directly affects how resilient your business is to cyberattacks.
The market offers dozens of products with similar descriptions, but they differ widely in threat coverage and analysis depth. This article breaks down what tasks email security should handle, which criteria to use when comparing solutions, and what to watch for during deployment.
Threats the Solution Should Cover
Before choosing a product, it's important to clearly define the current threat landscape. Modern email-based attacks fall into several categories.
Mass spam and phishing. Messages go out by the thousands — the attacker's goal is simply to get a random click on a link or a random attachment opened. Reputation-based filtering and signature analysis handle this category well.
Spear phishing. The attacker studies the target and sends a personalized message — posing as a colleague, a partner, or a regulator. This kind of message doesn't appear in mass threat databases, so standard filtering lets it through.
BEC (business email compromise). The attacker impersonates a senior executive or the finance department and requests a wire transfer or confidential data. The message usually arrives without malicious attachments or links, so traditional antivirus doesn't notice it. For more on this threat class, see Phishing and BEC Protection.
Spoofing. The attacker forges the sender address — either technically (the From header) or visually (a domain that resembles the original, e.g. bi-zone.com instead of bi.zone). SPF, DKIM, and DMARC checks close off a significant share of these scenarios.
Malicious attachments. Office documents with macros, archives containing executables, PDFs with exploits — dynamic analysis in an isolated environment (a sandbox) is what catches these.
A solution that doesn't cover all of these categories leaves significant blind spots in your defenses.
Key Technical Capabilities
When evaluating solutions, look for the following set of capabilities.
Sender authenticity verification. The solution checks SPF, DKIM, and DMARC records on incoming mail and helps you configure them for outgoing mail. A DMARC policy set to reject or quarantine blocks most spoofing scenarios.
Reputation analysis. Checking the sending server's IP address and domain against reputation databases is a fast way to filter out known spam and phishing sources before the message content is even analyzed.
Content filtering. Analyzing the message text, headers, and metadata reveals signs of phishing and fraud — even when the message contains no malicious attachments. Heuristics and machine learning catch attacks that haven't made it into signature databases yet.
Link analysis. Links in messages are checked at delivery time and, if the solution supports time-of-click analysis, again at the moment the user clicks. This covers the scenario where a phishing site is activated only after the message has already passed initial screening.
Dynamic attachment analysis. Suspicious files run in an isolated environment that records their behavior: calls to external servers, registry changes, child processes spawned. This is how threats not yet in signature databases get detected.
Quarantine and retrospective analysis. Suspicious messages are held in quarantine until the check completes. Retrospective analysis makes it possible to pull messages that already reached the inbox — if the threat is identified later, for example after a database update or once sandbox analysis finishes.
For a detailed look at how each of these mechanisms works, see What Is Mail Security.
Architecture Options and Integration
Email security solutions come in several architectural models — the choice between them depends on your existing infrastructure.
Gateway. All inbound and outbound traffic passes through a dedicated mail gateway that filters messages before they reach the mail server. This model gives you maximum control and doesn't depend on the mail provider's API.
API integration. The solution connects to the mail system via API (Microsoft 365, Google Workspace, and similar) and scans mail after the fact or in near-real time. Deployment is faster, but some messages can reach the inbox before the check finishes.
Hybrid model. Combines a gateway for inbound traffic with API access for retrospective analysis and removal of already-delivered messages. This provides both preventive and after-the-fact protection.
When choosing a model, factor in compatibility with your current mail system, the option to integrate with a SIEM for centralized monitoring, and API support for automating incident response.
Evaluation Criteria for Comparing Solutions
Beyond technical capabilities, weigh a handful of operational factors.
False positive rate. A high false positive rate means legitimate messages end up in quarantine and staff spend time sorting through complaints. You can check this metric during a pilot project or by requesting data from the vendor.
Delivery latency. Dynamic attachment analysis takes time. It's important to understand the average delay when a suspicious file is detected, and whether it fits within your business process requirements.
Policy flexibility. The ability to configure rules by domain, user, or attachment type simplifies maintenance and reduces the administrator's day-to-day workload.
Logs and reports. A detailed event history helps with incident investigations and with demonstrating the effectiveness of the protection to management.
Employee training. Some solutions include phishing simulation modules that help assess staff awareness and reduce the risk from social-engineering-based attacks. Technical filters are no substitute for a trained user who notices the signs of manipulation.
Database freshness. Threats evolve quickly. Ask how often the vendor updates its reputation databases and machine learning models, and how fast it responds to new campaigns.
Frequently Asked Questions
Why do I need email security if we already have corporate antivirus?
Antivirus on a workstation catches threats after a file has already reached the device. Email security acts earlier — at the delivery stage, before the user even opens the message. Antivirus also doesn't analyze message content, headers, or links — it works with files on disk, not with mail traffic.
What is DMARC, and do I need to configure it?
DMARC is an email authentication policy: it tells the receiving server what to do with messages that fail SPF and DKIM checks. Without DMARC, an attacker can easily spoof your domain in the From field. Configuring DMARC is a baseline step for protecting outgoing mail and your domain's reputation.
How does spear phishing differ from a mass mailing?
A mass mailing isn't personalized — the same message goes out to thousands of recipients. Spear phishing is crafted for a specific person or organization: the attacker studies publicly available information and builds a convincing context. These messages more often slip past reputation filters precisely because they aren't sent from a known spam source.
What happens if a threat is identified after the message has been delivered?
Retrospective analysis flags that a previously delivered message turned out to be malicious, and removes it from users' mailboxes either automatically or on an administrator's command. This matters most for attacks with delayed activation, where a phishing site or malicious file becomes dangerous only after delivery.
How do I check that a solution handles BEC attacks?
BEC messages most often contain no links or attachments — the attacker relies solely on text and impersonation of a real sender. Content and header analysis, along with behavioral models, are what catch them. When evaluating a solution, check how it responds to executive impersonation and domain spoofing when the message body contains no malicious objects.
Hands-On Practice in BI.ZONE Cybersecurity Labs
Understanding these selection criteria sticks best through hands-on practice. In the course, you work through real corporate email attack scenarios and see how BI.ZONE Mail Security responds to each one — from sandboxing a suspicious attachment to retrospectively removing a message that has already been delivered.