How email security works
Inbound messages are scanned before delivery. Filters check sender reputation, authentication records, message content, links and attachments, and may detonate files in a sandbox. Messages judged malicious are blocked or quarantined, while suspicious ones may be tagged or have links rewritten for time-of-click checks.
Outbound controls complement this. Encryption protects sensitive messages in transit, and data loss prevention rules can block or flag messages containing personal or financial information. Authentication standards help receiving servers reject spoofed mail that claims to come from your domain. Link rewriting and attachment sandboxing add a second look at content that appeared safe at delivery but turns malicious later, which is a common evasion tactic.
Why it matters for Canadian organizations
Email remains a common route for credential theft, business email compromise and malware delivery. A single stolen mailbox can expose customer records, which may trigger breach reporting duties under PIPEDA and Quebec Law 25 when there is a real risk of significant harm.
The Canadian Centre for Cyber Security regularly highlights phishing as a leading entry point for incidents. Because attackers target staff directly, technical filtering alone is not enough, and organizations also need training and clear reporting channels. Business email compromise often involves no malware at all, only convincing wording and a spoofed or hijacked account, so technical and procedural checks such as call-back verification for payment changes are valuable.
How to implement it
Layer controls. Publish SPF, DKIM and DMARC records and move DMARC toward an enforcement policy, deploy a filtering service that inspects links and attachments, and require multi-factor authentication on every mailbox.
Add user-focused measures: run phishing simulations, make it easy to report suspicious messages, and monitor for unusual mailbox rules or forwarding. Review alerts continuously so a compromised account is contained quickly. Review mail flow logs for forwarding rules, impossible-travel sign-ins and unusual sending volumes, since these often reveal a compromised account before users notice.
Frequently asked questions
What is the difference between SPF, DKIM and DMARC?
SPF lists the servers allowed to send mail for your domain. DKIM adds a cryptographic signature to messages. DMARC tells receivers what to do when SPF or DKIM checks fail and sends you reports. Together they reduce spoofing of your domain.
Does Microsoft 365 or Google Workspace include enough email security?
Both include baseline filtering, and many organizations find it adequate for commodity spam. Targeted phishing, business email compromise and malicious links often warrant additional layers, stronger configuration and monitoring. The right level depends on your risk and the data in your mailboxes.
Can email security stop all phishing?
No control stops everything. Filters catch most bulk threats, but well-crafted targeted messages can slip through. That is why layered defenses matter: multi-factor authentication, user reporting, mailbox monitoring and a practiced response plan limit the damage when one gets through.
Related service: Email security