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What Is Secure Email? Guide To Email Encryption And Authentication

Posted by Picture of Sam Kendall Sam Kendall

Secure email solutions use email encryption and identity authentication to protect email contents from interception, manipulation, and error, and to ensure messages are delivered to the right people.

Secure email services often include other features such as outbound email risk warnings, message audit trails, and access controls to provide additional protections against the most common threats.

They are vital for robust outbound email security.

Who Is Secure Email Designed For?

Secure email solutions can be used by anyone who needs to send sensitive information or documents and ensure that they reach the right people.

Most often though, secure email is used by businesses that regularly deal with confidential customer information and have a duty to protect it.

Businesses are duty-bound to protect personal information

Secure email solutions enable you to deliver information to customers, colleagues, and partners without exposing it to email risk.

Why Is Secure Email Important?

Email was invented in 1976 but is now one of the most widely used communication tools by both consumers and businesses.

It was never designed with the security of sensitive data in mind.

Email providers have added measures over the years to reduce risks. However, the core technology of the email network still leaves sent messages vulnerable to interception, manipulation, and error.

the history of email

Furthermore, as society increasingly depends on email, the amount of sensitive data being sent has grown. This expansion presents cyber criminals with numerous opportunities for exploitation.

A secure email solution provides protection against these threats, ensuring that email messages always reach the right people, safely.

How Does Secure Email Work?

Secure email services work just like email, with added security.

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The most common features associated with secure email include:

End-to-End Email Encryption

Encryption is the process of scrambling an email message and any attached files so it can't be accessed by third parties.

End-to-end encryption is when email content is encrypted directly on the sender’s device before being sent, and only decrypted once it lands in the recipient’s mailbox (from one end to the other).

End-to-end encryption ensures that email data remain safe, as it can't be accessed even if a message is intercepted.

Learn more about email encryption.

Email Authentication

Email authentication methods are vital for verifying identity in secure email solutions, and can play different roles:

  • Account authentication can be used to add an extra layer of security to an email account itself, during the login process.
  • Recipient authentication is used to verify the identity of email recipients before they can unlock encrypted messages.

Secure email services can provide multiple options for authenticating the identity of email recipients including the use of SMS codes, identity documents, and question-and-answer challenges.

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Authentication methods enable secure email users to ensure the people with access to email contents 'are who they say they are'.

This is especially important for businesses that must prove information is delivered to the right people for regulatory compliance.

Learn more about email authentication.

Email Revoke

Email revoke allows you to block access to a message after sending it.

Email revoke can protect data in scenarios that commonly cause data breaches, such as sending a message to the wrong person.

Unlike email recall, which is limited and dependent on specific conditions (like a message being unopened), secure email solutions can offer comprehensive email access management functionality.

Secure email solutions can offer full email revoke, enabling users to block access to any message anytime, even after it’s been opened.

Not only does this provide a recovery method for the worst kind of mistake, it gives email users peace of mind that if they do make an error, there is a way to take it back.

Learn more about why email revoke is important.

Email Audit Trails

Secure email solutions can provide comprehensive logging and reporting capabilities to assist with auditing and regulatory compliance.

For example, some may record all recipient interactions with a message including opens, downloads, and revoke calls.

Senders can track the status of outbound emails and opt to receive notifications when their messages are opened.

In sectors such as financial services, audit trails are vital as confirmation of delivery is required for many transactions.

Learn more about financial services email compliance.

Email Risk Warnings

Secure email solutions can provide senders with warnings regarding the risk of their outbound messages.

A solution will scan the contents of an email message for common criteria associated with sensitive information and suggest appropriate security measures that should be applied.

Some solutions are also designed to ask senders to double-check recipient email addresses before pressing 'send'.

These warnings can provide vital prevention capabilities at the same time as training users to take care with outbound data.

Learn why personally identifiable information needs protecting.

What Cyber Threats Can Secure Email Protect Against?

Secure email solutions are designed to protect data against the most significant and concerning email risks.

Phishing Attacks

In a phishing attack, a malicious third party sends an email impersonating a legitimate source, such as a bank or reputable company.

They attempt to trick the recipient into clicking a link or giving up sensitive information, including passwords or financial information.

According to research, 81% of organisations around the world have experienced an increase in email phishing attacks since 2020.

Phishing is the most reported method of cyber attack

Email authentication can create a trusted connection between senders and recipients so they can ensure messages are legitimate.

Email Interception

Email interception is when an attacker interrupts the communication between two parties, allowing them to eavesdrop on the conversation or modify the contents of messages.

When information is transmitted in an unsecured email, attackers can gain access without the sender or recipient being aware.

End-to-end email encryption protects messages from interception by locking the contents before they are sent.

Human Error

Many people will relate to the ‘oops!’ moment when you realise you've sent an email message to the wrong person.

Studies show that over 88% of all business data breaches are caused by employee mistakes. These incidents can result in reputational damage and fines if emails contain customer information.

Email revoke and email risk warnings can prevent sensitive data from being sent in error (or misdirected).

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Recipient authentication can also help in instances of email misdirection, as even if emails are sent to the wrong address, they may not be able to be opened by any unintended parties.

What Email Data Needs Protecting?

There are specific types of data that are considered sensitive under UK law and regulatory guidelines.

It is important for businesses and their employees to be aware of what sensitive data is, so it can be protected.

Personal Data

Personal data includes any information that can be used to identify an individual, such as name, address, or phone number.

Cyber criminals can use this type of information to commit identity theft or for other fraudulent purposes.

Financial Data

Financial data includes any information related to wealth and financial transactions including bank account details and credit card numbers.

Third parties who can gain access to this data can create fraudulent accounts, steal funds, and commit a host of financial crimes.

Medical Data

Medical data is usually associated with medical records and contains sensitive information including personal data and health history.

Legal Data

Legal data is usually associated with legal documents such as contracts and contains information related to legal proceedings.

Intellectual Property Data

Intellectual property includes information relating to proprietary assets such as patents, trademarks, and copyrights.

Industry Focus: Financial Services

As an industry dealing with large amounts of sensitive information, it’s easy to see why the financial services is a target for threat actors.

What documents do you use secure email to send?

When asking our financial services customers what type of documents they use secure email to protect, we found that:

  • 45% regularly protect anti-money-laundering documents;
  • 61% regularly protect proposal and policy documents;
  • 42% regularly protect investment valuations;
  • 50% regularly protect banking details.

It's clear that for financial services professionals, exchanging sensitive information by email is critical to business.

What Are The Consequences Of Failing To Protect Data?

The Information Commissioners Office (ICO) can impose fines of up to £17.5 million or 4% of their annual turnover for businesses who do not apply appropriate protections to their data.

While the financial impact of a breach or attack can be severe and substantial, the reputational damage can be worse.

business reputation to recover after a data breach

Businesses that fail to adequately protect client privacy see acquisition and retention levels fall, and the impact can be long-lasting.

What Is The Best Secure Email Solution?

If you're looking for the best secure email service for your business, there are some key criteria to consider.

Encryption Strength

Many email providers natively use TLS (transport layer security). Others use PGP (pretty good privacy). These are both forms of encryption.

However, these encryption types are not considered secure enough alone to protect sensitive data due to established vulnerabilities.

Though they offer strong protection for messages in transit, TLS and PGP may not be enough to protect emails at rest on mail servers.

For robust security, messages should be secured with at least AES-256 encryption, the standard used by the military.

Learn more about email encryption.

Authentication Type

Depending on the level of security and flexibility you need, you should also be mindful of authentication methods.

Do you want recipients to authenticate themselves using an SMS code, using a secret, or by providing biometric data such as a fingerprint?

Each of these has trade-offs in terms of ease of use and security.

Learn more about email authentication.

Integration Options

Exploring the integration capabilities of a secure email solution is key to ensuring operational efficiency for your organisation.

For example, our own solution offers an integration with Unipass Identity, a single-sign-on for professionals in the financial sector.

Learn more about our secure email integrations.

Ease Of Use

An unbreakable secure email solution is ineffective if it's not user-friendly for both senders and recipients.

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Offering a solution that doesn’t seamlessly fit into pre-existing workflows runs the risk of being circumvented by users.

Choosing a secure email tool that provides the right user experience is vital for embedding it within core processes.

Read our complete guide to the best secure email services.

Securing Your Emails - Essential To Business Operations?

With the increasing risks of phishing, interception, and human error, coupled with the strict penalties for data breaches, investing in a robust secure email solution is more than a best practice – it's a critical component of modern business operations.

By offering a solution with strong encryption, versatile authentication, and user-friendly features, organisations can protect sensitive data. This helps them comply with regulatory requirements and maintain their reputation.

Embracing secure email is a proactive step towards safer, more secure digital communications for businesses and consumers.

Update For Clarity (22.03.2024):

Are TLS and PGP not secure?

Not entirely. They offer valuable security measures, especially for encrypting data in transit. However, for highly sensitive information, secure email solutions often recommend stronger encryption standards like AES-256. This military-grade encryption offers a higher level of protection for message content, even if someone were to gain access to the email server.

Choosing the Right Encryption:

The appropriate encryption level depends on the sensitivity of the information you're sending. Here's a general guideline:

  • For low-risk information: TLS might be sufficient.
  • For moderately sensitive information: Consider S/MIME (Secure/Multipurpose Internet Mail Extensions) or PGP, which encrypt the message content itself.
  • For highly sensitive information: Secure email solutions often recommend strong encryption standards like AES-256 for maximum protection.

Deliver sensitive information securely with Mailock


Cyber security breaches survey 2023, UK Government, 2023

Data Security: An Analysis of 2022 ICO Breach Reporting, Beyond Encryption, 2023

50 Phishing Stats You Should Know In 2024, Expert Insights, 2023

Stanford Research: 88% Of Data Breaches Are Caused By Human Error, KnowBe4 Blog, 2021

The Devastating Business Impacts of a Cyber Breach, Harvard Business Review, 2023

Reviewed By:

Sabrina McClune, 05.06.24

Sam Kendall, 05.06.24


Originally posted on 14 12 22
Last updated on June 19, 2024

Posted by: Sam Kendall

Sam Kendall is an expert researcher, editor, and marketing specialist. He has worked with B2B brands for almost a decade helping them to refine their digital strategy and streamline ground-level implementation. Sam is passionate about new developments in user experience, demand generation marketing, and customer communications.

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