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101 Guide
8 min

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, ensuring messages are delivered to the right people.

Secure email software often includes additional features such as outbound security triggers, audit trails, and access control to provide additional protections against the most common email risks.

Who is secure email designed for?

Secure email software can be used by anyone who needs to send sensitive information or documents and wants to ensure that they reach the right people. Most often, secure email is used by businesses in regulated sectors that regularly deal with confidential data.

IT professionals discussing secure email integration

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

Why is secure email important?

Email was invented a long time ago and is now one of the most widely used communication tools by both consumers and businesses. Unfortunately, it was never designed with the security of sensitive data in mind.

Society has developed a growing dependence on digital communication and services, and so emails containing sensitive information continue to be sent ‘in the clear’ (unsecured). This presents a valuable opportunity for malicious actors who look to exploit personal information.

Cybercriminals are constantly developing more sophisticated methods of attack, with 39% of UK businesses becoming victims of cyber attacks in 2022. Unsecured email remains at risk from interception and phishing attempts - not to mention that misdirected emails from unwitting senders are contributing to a high number of data breaches.

A secure email solution provides protection against these threats, ensuring that email messages remain secure and confidential.

How does secure email work?

Secure emails work just like normal emails, with some added security benefits. These include:

End-to-end encryption

End-to-end encryption is the process of scrambling an email message and any attached files. This disguises sensitive content from third parties and protects sensitive data from interception and theft.

End-to-end encryption is superior in that email content is encrypted directly on the sender’s device before being sent, and only decrypted once it lands in the recipient’s mailbox.

The decryption and encryption process is carried out using specific keys, which are only accessible to the sender and recipient. This ensures that emails can only be read by the intended people and makes them inaccessible to third parties who attempt to intercept or otherwise gain access to communications.

Read more about encryption...


Authentication has multiple use cases in secure email solutions. Multi-factor authentication can be used to add an extra layer of security to an email account itself, during the login process. It can also be used to verify the identity of email recipients.

To obtain the right key to unlock an encrypted email message, the recipient must pass an authentication challenge. This typically requires the recipient to prove they 'are who they say there are', usually by answering a question or entering an SMS code sent to their mobile.

Authentication is important in situations where sensitive or confidential information is being sent via email and the sender wants to ensure that the message is only accessed by the intended recipient.


Revoking an email allows you to block access to a message after sending it. In most email clients, such as Gmail and Outlook, recall is limited and only possible under specific circumstances, such as if the recipient hasn't opened the email yet, or if the recipient uses the same email provider.

Many secure email solutions offer users full email revocation, enabling users to retrieve a message and block access completely – even after it’s been opened. Message revoke can prevent sensitive data from being accessed by unintended recipients, which is especially important in a business context where sensitive information is being exchanged.


Secure email solutions are useful for maintaining regulatory compliance, as they can provide comprehensive logging and reporting capabilities. Recipient interactions are recorded, including opens, downloads, and revoke calls. Senders can track the status of outbound emails and receive notifications when messages are opened or files are downloaded.

This information can be used to generate reports for audits that demonstrate compliance with regulatory requirements and internal policies. In sectors such as financial services, this is especially important, as confirmation of delivery is required in many processes.

Trigger words

Trigger words, otherwise known as security phrases, are sometimes used in secure email solutions to automatically trigger the encryption process for a message. The secure email system automatically scans the contents of a user’s email messages for specific keywords or phrases, such as ‘confidential’ or ‘private’. When a trigger word is detected, the email is automatically encrypted, so sensitive data is kept secure.

This feature can be especially useful for businesses that handle sensitive information on a regular basis, such as healthcare or financial institutions. By using trigger words, these organisations can ensure that sensitive information types are reliably protected, regardless of whether the sender remembers to manually encrypt the message.

What cyber threats does secure email protect against?

Secure email solutions are vital for securing communications against a variety of digital risks, including:

Phishing Attacks

Phishing is one of the most common types of cyber-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. Secure email solutions utilise authentication to create trusted connections between businesses and consumers so that users can be confident whether a message is legitimate or not.


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

When sensitive information is being transmitted by unsecured email, an attacker can gain access without the sender or recipient being aware. By utilising the encryption capabilities that secure email solutions offer, users can protect against interception and ensure that only the intended recipient reads their messages.

Misdirected emails

Many people will relate to the ‘oops!’ moment when you realise you've sent an email message to the wrong person. In fact, studies show that 88% of all data breaches are caused by employee mistakes.

 If the email in question includes sensitive information, this can often result in a data breach and can have serious repercussions for the sender.

According to our research, a quarter of UK consumers have sent sensitive data over email to the wrong recipient. Using the email revoke function of a secure email solution ensures that messages sent in error are recalled, removing the recipient's access and preventing data leakage.

What data needs protecting?

Man staring at computer screen

When considering what types of data need protection from cyber threats, the following types are generally considered to be the most vital:

  • Personal data - includes any information that can be used to identify an individual, either on its own or in conjunction with other types of data, such as name, address, or phone number. Cybercriminals can use this type of information for identity theft or other fraudulent purposes.
  • Financial data - includes aspects such as bank account details and credit card numbers. Third parties who can gain access to this type of information can create fraudulent accounts, steal funds, and commit a host of financial crimes.
  • Medical records - contain highly sensitive information, including a variety of personal data and health history.
  • Legal documents - contain sensitive information related to legal proceedings, such as contracts, court documents, and briefs.
  • Intellectual property – valuable assets such as patents, trademarks and copyrights.

Industry focus: financial services

Our latest survey reveals that 21% of UK consumers have been asked by a financial services professional to send personal data over email.

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 – especially when many organisations still use unsecured email.

Designed for financial services businesses, Mailock is a secure and easy-to-use secure email solution. When asking our current customers what type of documents they protect with Mailock, 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

Financial services usage of secure email by type of doument

What are the consequences of failing to protect data?

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

For organisations within data-heavy industries such as financial services, legal and medical, restrictions and regulations are especially stringent in order to protect sensitive client information.

While the financial impact of a breach of attack is substantial, the reputational damage can be worse. Businesses that fail to adequately protect client privacy see acquisition and retention levels fall - a situation that can take them time from which to recover.

What's the best secure email solution?

When considering protection for your emails, there are several key elements 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, they are no longer considered completely secure due to vulnerabilities and a lack of protection for emails at rest. For truly secure email, messages must be secured with at least AES-256 encryption.

Authentication types.

Depending on the level of security and flexibility you need, you should also be mindful of authentication types. Do you want recipients to authenticate themselves using an SMS code, by answering a secret question, or by providing biometric data such as a fingerprint? Each of these has pros and cons in terms of ease-of-use and security.


Depending on your organisation, looking into which integrations a secure email solution has can help your operations run smoother. For example, Mailock offers a unique integration with Unipass Identity, a single-sign-on for professionals in the financial sector.


A product can have all the security in the world, but if it’s not easily used by your staff, it doesn’t make a difference. People prefer frictionless processes. Offering a solution that doesn’t seamlessly fit into pre-existing workflows runs the risk of being ignored by staff.


Originally posted on 14 12 22
Last updated on July 26, 2023

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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