Interscale Content Hub – The urgency of best email security practices is increasingly important today. This is not just a claim because according to the many reports, email is one of the targets of phishing attacks.
A report by Patrick Nohe and Ross Thomas in “Email Security Best Practices”, shows an alarming 91% of cyberattacks start with phishing emails. Meanwhile, FBI report states that phishing scams were the highest cybercrime in 2020. The losses were huge, reaching more than $ 4.2 billion. The way email attacks work varies, such as suspicious email attachments, containing infected URLs, and social engineering.
Your company can avoid similar losses due to phishing by implementing email security best practices. In this article, I will provide a comprehensive guide.
What are the 3 Email Safety Rules to Stay Safe?
Before you look into advanced defenses, lock down the fundamentals with several core email safety best practices.
- Be Cautious with Links and Attachments: Always pause and think before you click. If an email—even one from a trusted sender—seems off, skip the link or attachment. Cybercriminals hide malware in what looks harmless. Playing it safe stops many phishing and malware infections.
- Use Strong and Unique Passwords: Your email password is your first line of defense. Make it long, complex, and never reuse it elsewhere. Weak passwords give hackers easy access. Gartner predicts stolen credentials will soon be the top fallout from phishing attacks. A robust password policy is non-negotiable.
- Keep Software Up to Date: Regular updates for your email client, antivirus, and operating system aren’t optional—they’re essential. Security patches close the door on vulnerabilities that hackers exploit. Organizations delaying updates leave a gaping entry for attacks. Stay current to keep your defenses tight.
Key Email Security Best Practices for 2025
Beyond these three fundamental rules, let’s look at some key email security best practices you can use to strengthen your defences.
Implement Strong Email Authentication
Ever wonder if that email is truly from who it claims? That’s why email authentication is crucial. It ensures every message in your inbox is genuine—no imposters allowed. Here’s how to lock it down:
- SPF (Sender Policy Framework): This protocol tells mail servers which systems are allowed to send email on your behalf. It stops scammers from faking your domain.
- DKIM (DomainKeys Identified Mail): Adds a unique digital signature to every outgoing email. The recipient’s server checks the signature to confirm the email hasn’t been tampered with.
- DMARC (Domain-based Message Authentication, Reporting & Conformance): Builds on SPF and DKIM by instructing receiving servers on how to handle emails that fail authentication. With DMARC, you can quarantine or reject suspicious messages and get reports on any unauthorized activity.
By setting up these three layers, you greatly reduce the chance of phishing emails pretending to be from you. No one should ever send emails “as you” except you—and these tools enforce exactly that.
Use Encryption
Encryption is a way of keeping your email communications private by making them unreadable to people who shouldn’t see them. There are two email encryption methods:
- Transport Layer Security (TLS): Encrypts the connection between mail servers, so your emails are safe while they’re being sent.
- End-to-End Encryption (E2EE): This encrypts your emails on your device, so they stay encrypted until the recipient decrypts them.
The choice between TLS and E2EE depends on how sensitive the information you’re sending is and what your company’s specific security needs are.
Deploy Anti-Malware and Anti-Virus Solutions
It’s a good idea to invest in a solid email security solution with anti-malware and anti-virus scanning capabilities. These solutions scan incoming emails for malicious software and known viruses. So you can stop them from reaching your inbox and causing any problems on your systems.
On top of that, sandboxing is another way to keep your network safe. It lets you open suspicious attachments in a safe, isolated environment to see what they do before letting them into your network.
There are several Anti-Malware and Anti-Virus Solutions that we recommend, including:
- Time Zero Virus Protection
- Check Point Harmony
- Cisco Secure Email
Implement Data Loss Prevention (DLP)
DLP for email stops confidential info from leaving your organization, whether by accident or design. It monitors outgoing emails and attachments for the keywords, patterns, or data types you define as sensitive. In short, DLP is a must-have email security best practice that protects your business from leaks, keeping your data safe and your team empowered.
Imagine setting up DLP rules that flag emails with financial details like credit card or bank account numbers, personal identifiers like tax file numbers, or secret project codes. If an employee hits send on a risky email, the system either halts it or alerts a security admin. This guard stops accidental sharing of customer data, intellectual property, and regulated info.
Using DLP is like having a vigilant digital bouncer. With the right trigger, motivation, and ease-of-use—the core of the Fogg Behavior Model—it nudges your team to double-check before sending. It ensures that only approved information exits your organization.
Use Multi-Factor Authentication (MFA)
Multi-factor authentication is like adding a solid deadbolt to your front door. This requires users to provide multiple forms of evidence to verify their identity. MFA usually involves a combination of something they know (like a password) and something they have (like a code sent to their phone).
A study by Suzuki et al., found that companies using MFA had fewer successful phishing attacks because it adds another layer of security. Suzuki and colleagues show how MFA, with its multiple verification factors, makes it much harder for hackers to get access even if they get a user’s password.
Regularly Update and Patch Email Systems
Nohe and Thomas point out a common tactic used by successful malware-based phishing attacks is to target outdated software. So, keeping your software up to date with regular patching and updates can help to prevent such exploits.
Adobe PDF, Flash, and Java are some of the most commonly exploited software, with up to a 75% increase in attacks when not regularly updated. Making sure your company keeps up with software updates helps to reduce these risks a lot.
Conduct Employee Training and Awareness Programs
Nohe and Thomas have found some pretty surprising stats: 70% of US employees don’t have a basic grasp of cybersecurity best practices. This shows just how important it is to have comprehensive training and awareness programmes in place for your employees.
In this case, you need to know the 7 components of effective cybersecurity awareness training programs.
- Tailored Content
- Engaging Formats
- Real-World Examples
- Regular Updates
- Practical Application
- Measurement & Improvement
- Positive Reinforcement
That way, it helps to create a culture of cybersecurity vigilance within your organisation.
Monitor and Analyze Email Traffic
Monitoring and analysing email traffic helps you spot any weird or suspicious activity that could be a sign of a security breach or ongoing attack.
Gartner suggests using Integrated Cloud Email Security (ICES) solutions that use machine learning (ML) and natural language processing (NLP) to analyse emails for anomalies. These tools spot when accounts have been hacked and show users context-specific banners that help them make smart choices about the emails they get.
Develop and Enforce Email Security Policies
A clear, written email security policy is your roadmap for how everyone in the organization should use email safely. It sets expectations and procedures for both everyday email usage and security incidents. Surprisingly, many companies lack formal email security policies.
Let’s check one case in point. The infamous $3 million CEO fraud phishing scam at Mattel. Attackers impersonated Mattel’s CEO via email and convinced an employee to wire money to a fraudulent account. If strict verification policies had been in place (and followed), that could have been prevented.
Your policy should cover things like:
- Acceptable Use: What employees can and can’t do with company email (e.g. no auto-forwarding work emails to personal accounts, no clicking unknown links).
- Password and MFA Requirements: Enforce strong passwords and multi-factor authentication as we discussed earlier.
- Handling Sensitive Information: Guidelines on when to use encryption, how to share confidential files (or when not to use email at all for certain data), and who is authorized to do so.
- Email Verification Procedures: For example, if finance receives an email requesting a funds transfer, the policy might require verifying via a phone call or a secondary channel before action.
- Incident Response Steps: Instructions for what employees should do if they suspect a phishing email or if they accidentally click something malicious.
Once you develop this email security policy strategy, enforce it consistently. Train employees on the policy’s contents so they understand the why behind each rule. Regularly revisit and update the policy as new threats emerge or as your business needs change.
For more guidance on crafting email usage rules, see our article on email security recommendations – it covers standard and advanced policies to consider.
Using Most Secure Email Providers
Using the most secure email providers is one of the most proper method to avoid ransomware. One of the most fundamental features we should pay attention to when choosing a provider is end-to-end encryption, which means only the sender and intended recipient can read the message content.
The good news is, there are plenty of options. Here are some secure email providers that implement the ASD Manual and the Spam Regulations 2021.
- Protonmail
- Tutanota
- Fastmail
- Hushmail
- Mailfence
Email Security Strategy: What to Do If an Attack Occurs?
Implementing the preventive measures above will greatly improve your security, but no strategy is 100% foolproof. Email security for small business and enterprises alike must include an incident response plan. In other words, everyone should know what to do if you’ve been attacked or suspect a malicious email got through. Quick, calm action can contain the damage. Here’s an “attack happened” email security strategy to follow:
Do Not Interact
If a suspicious email does slip in, do not click any links or open attachments. Also avoid replying to the sender. Interacting with a malicious email can trigger malware or confirm to the attacker that your address is active. It’s best to leave the email untouched while you proceed with the next steps.
Verify the Source
Double-check the sender’s address and any information in the email. Often, scam emails use an address that’s off by one letter or from an odd domain that impersonates a legitimate one.
For example, an email might come from billing@paypa1.com (with a “1” instead of “l”). If the message claims to be from a known partner or colleague but something seems off (unexpected request, urgent tone, spelling errors), contact that person or company through a trusted channel (like calling them) to see if they actually sent it. Never trust the email at face value if you have doubts.
Report the Email
Don’t keep a suspected phishing or malware email to yourself. Notify your IT or cybersecurity team immediately so they can investigate and warn others. Most email clients (Outlook, Gmail, etc.) have a “Report phishing” or “Mark as spam” button – use that as well, as it helps train the system and may alert the provider to block similar messages. Early reporting can prevent others in your organization from falling for the same trick.
Isolate the Email
After reporting, it’s wise to isolate the threat. Do not forward the email to anyone (except perhaps to IT security, and even then, follow their instructions, as they might prefer you simply screenshot the content). Move the email out of your main inbox into a quarantine folder or label it as suspicious.
This way, you won’t accidentally click it later, and it’s clearly marked if someone else ends up looking at your mailbox. Some companies have a procedure to drag and drop such emails into a dedicated “Phishing” folder that the security team monitors.
Scan Your System
If you did click a link or open an attachment (or you just want to be extra safe), run a full antivirus/malware scan on your computer. Make sure your security software is updated to the latest virus definitions, then do a comprehensive scan.
These approaches will help catch and remove any malware that might have been activated. It’s better to do this immediately rather than waiting for the symptoms of an infection. If your scan finds something, follow the antivirus prompts to quarantine or remove the threat, and inform IT about what was found.
Change Passwords (If Necessary)
If you fear that your email account credentials might have been compromised (for example, you entered your login on a fake webpage that a phishing email led you to), change your password right away. Update it to a new, strong password that you haven’t used before.
Additionally, if you use that same password anywhere else (which you ideally shouldn’t, but if you did), change it on those accounts too. This is where having MFA is crucial – if an attacker did steal your password, they still can’t get in without the second factor, giving you time to lock them out by changing the password.
Educate Yourself and Your Team
Every incident, even a close call, is a learning opportunity. Take time to understand how the attack worked and how you can avoid similar situations. Share the experience with your team so others know what to watch for. If your company offers refresher cybersecurity training after an event, take it seriously. The goal is to continually improve your collective defenses. Remember, cyber threats evolve, so ongoing education is part of a strong email security strategy.
Monitor Accounts and Follow Up
After an attempted attack, keep an eye on relevant accounts and systems for a while. For instance, if the phishing email was trying to steal banking info or personal data, monitor your bank statements and credit reports to ensure no fraudulent activity occurs.
If any customer or employee data may have been exposed, have a plan to alert those affected and guide them on protective steps. It’s also wise to review your email filtering and security settings after an incident to see if any adjustments can be made to prevent a similar one in the future.
Strengthening with Interscale
You don’t have to do it all alone, either. Interscale’s experts are here to help fortify your email defenses. Our Email Security & Protection Services across Australia provide an all-in-one solution to implement these best practices, from enterprise-grade spam filtering and encryption to user training and policy development. We tailor our services to fit small and medium businesses, giving you the same level of security as a big enterprise without the complexity.
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