Email encryption: which method fits when – and why standard is not enough

According to Bitkom , an average of 53 emails land in German business inboxes every day – and the trend is rising. Many of these contain sensitive information: contracts, personnel data, patient records, or financial documents. With every single one, the same question arises, yet in practice, it is rarely answered consistently: is this email sufficiently protected?

The problem is seldom a lack of awareness. Rather, it is the sheer variety of available methods and the fact that complex security decisions are often left entirely to the user. TLS, S/MIME, PGP – for those who don’t deal with IT security on a daily basis, it’s easy to lose track. When in doubt, no decision is made at all. This is where email encryption becomes a stress factor.

This article provides a clear overview: how email encryption works, which method is suitable for which situation, and how encrypted emails can move from being a daily hassle to an efficient, automated routine.

TL;DR – the essentials at a glance:

• Many companies use email encryption incorrectly or not at all because, in the heat of the moment, no one consistently decides which method is appropriate.

• TLS is the standard basic protection for the transport route – but it does not protect the content. It is sufficient for routine emails, but not for sensitive data.

• S/MIME protects content and attachments end-to-end and is the gold standard for regulated industries – but it is traditionally difficult to manage.

• PGP offers strong encryption without a central certification authority; however, it is primarily suitable for tech-savvy partners rather than general corporate use.

• Integrated email encryption with FTAPI solves the underlying problem: the system decides in the background which method fits, without requiring user intervention.

What is an encrypted email – and why is "standard" often insufficient?

An encrypted email ensures that its content (text and attachments) can only be read by the intended recipients. Without encryption, an email is like a postcard: anyone with access along the way can read it.

Encryption does not just protect against external attacks. It is also an internal signal: customers and partners notice when their communication is handled securely – and they draw conclusions about a company’s trustworthiness accordingly.

However, many underestimate the fact that not all encryption is created equal:

• Transport encryption only protects the email’s transmission path – meaning all data exchanged between client and server is protected during transit. The content itself remains unencrypted.

• End-to-end encryption protects the content itself: the email is encrypted directly in the sender's email programme and only decrypted on the recipient's device. It remains encrypted at all intermediate stages and on servers – no one except the sender and recipient has access.

Which of these two types of protection is sufficient depends on the content. And that is exactly the point: not every email requires the same level of protection. The question is which method makes sense for which use case.

Sending encrypted emails: an overview of methods

When it comes to encrypting emails, the right method depends on the recipient, the content, and the existing infrastructure. The three established standards – TLS, S/MIME, and PGP – cover different scenarios and each has clear strengths and limitations. Those who know when each standard is appropriate can make better decisions – or automate them entirely.

Tip: You can find more information on the pros and cons of the individual methods in the article "Encrypting email attachments: how to do it securely". Here, the focus is on practical application: what protects when and why.

TLS – transport encryption as basic protection

TLS (Transport Layer Security) is active with almost every reputable email provider today – and runs completely in the background. Users do not notice it; no settings are required. An encrypted connection is established between the email programme (client) and the email server. All data exchanged between the client and server is thus protected during transmission. TLS ensures that no one can "eavesdrop" along the way.

When TLS is sufficient:

• Routine coordination and standard communication

• Organisational coordination (e.g. appointments)

• Administrative communication without confidential content

• General customer and service information

When TLS is not enough:

• Contracts, offers, financial data

• Internal administrative documents requiring protection

• Health and personal data

• Financial and risk-relevant information

In short: TLS is the minimum standard – nothing more and nothing less. It is sufficient as basic protection for most normal business emails. Anyone sending sensitive data via email needs end-to-end encryption.

S/MIME – the gold standard for regulated communication

S/MIME (Secure/Multipurpose Internet Mail Extensions) is the most widely used standard for end-to-end email encryption in corporate environments. It is based on asymmetric encryption with digital certificates. Sender and recipient each possess a key pair. The recipient's public key is used for encryption, while the recipient's private key is used for decryption. Additionally, emails can be provided with a digital signature.

When S/MIME is the right choice:

• Corporate communication with high protection requirements

• In regulated industries such as healthcare (e.g. doctor ↔ health insurance provider), insurance, banking, or public authorities

When S/MIME is less suitable:

• Ad-hoc communication with external recipients without their own certificates

• Broad customer communication or public correspondence

• Small partners without PKI infrastructure

In short: S/MIME is the gold standard for regulated industries when strong authenticity and encryption are required. However, in its classic form and with manual certificate management, it is less suitable for broad everyday use with changing partners.

PGP – strong encryption for tech-savvy environments

PGP (Pretty Good Privacy, also OpenPGP) is an open standard that functions without central certification authorities. Users create their own key pairs and exchange public keys manually or publish them on key servers.

When PGP makes sense:

• Research and development collaborations with tech-savvy partners

• Scenarios where a deliberate lack of dependence on central certification authorities is desired

• Small, clearly defined communities or user groups with high technical expertise

When PGP does not fit:

• Companies with limited IT resources

• Regulated sectors with PKI requirements (e.g. banks, public authorities)

• Broad customer or public communication

In short: PGP is cryptographically very strong but hardly practicable in everyday corporate life. A lack of integration into common email clients, high training requirements, and complex key management make it a specialised tool rather than a standard procedure.

Integrated, automatic encryption with FTAPI

Platforms such as FTAPI bridge the gap between robust protection and ease of use: they utilise established technical standards and automate the encryption process in the background. The user benefits from automated end-to-end encryption without manual key exchange and without the constant need to decide which type of encryption is appropriate.

FTAPI acts as a central hub for secure email communication. It allows for the implementation of two fundamentally different approaches:

• User tool: Emails are encrypted directly within the email programme, thanks to Outlook integration. Employees decide upon sending whether the message and any attached files should be transmitted in an encrypted format.

• Mail flow integration: Encryption is embedded as a component within the mail flow. All outgoing messages are automatically scanned for sensitive content and encrypted if necessary (more on this later). Employees do not need to take any action; they simply compose and send messages as usual in their email programme.

When a platform like FTAPI is beneficial:

• Exchanging sensitive data with internal and external recipients.

• Sending very large files (e.g. CAD, expert reports, medical findings).

• Organisations with an S/MIME mandate (e.g. banks, healthcare).

When FTAPI is less suitable:

• Communication with no specific protection requirements.

In short: a platform like FTAPI combines the security of S/MIME and PGP with intelligent automation, ensuring that compliance requirements are met without the need for user intervention. It also satisfies the demands of strictly regulated industries, providing companies with a comprehensive solution for secure email communication.

The real problem: who decides in daily business?

The methods exist. So does the knowledge. Yet email encryption remains patchy in many companies. The reason rarely lies in the technology – it lies in practice.

With an average of over 50 emails per working day, every manual encryption decision becomes a potential vulnerability. When in doubt, employees are busy with their actual tasks, not with the question of which standard is technically appropriate for a specific recipient. According to the FTAPI Secure Data Report 2025, 56 per cent of companies cite technical complexity as a key hurdle in introducing secure communication solutions, while 43 per cent complain about a lack of user-friendliness.

The result: encryption is either not used at all or applied incorrectly. Both scenarios create security gaps.

How FTAPI implements automatic email encryption

FTAPI solves this problem by ensuring that the decision is made by the system rather than the user. This allows sensitive data to be exchanged reliably without employees losing valuable time on technical decisions. The FTAPI platform integrates into existing infrastructure as a system component and handles the decision of how emails must be encrypted – automatically, in real-time, for every single email.

Admins define the rules once: what needs to be protected and how? FTAPI then applies these rules automatically to every email and checks, for example, which infrastructure is available at the recipient's end. The appropriate method is then selected based on this information.

Employees notice no difference. No training is required, and there are no incorrect decisions. Additionally, every dispatch is documented in an audit-proof manner.

FTAPI is BSI C5 Type 2 audited, certified according to ISO 27001, 27017, and 27018, GDPR-compliant, and is hosted exclusively in Germany.

Conclusion: secure email communication does not need complexity

Sending encrypted emails is not a question of skill – it is a question of the system. TLS is sufficient for many routine communications. S/MIME is the standard for regulated communication with defined partners. PGP remains a tool for special cases. And for the rest of daily business and the hundreds of emails where no employee has the time or the expertise to make an encryption decision, a solution that thinks for itself is required.

True secure email communication arises when the technology moves into the background and compliance "just happens". In this case, simplicity is the best protection. After all, only a solution that is actually used provides real protection. By automating encryption, you make secure data exchange as natural as sending a standard email.