What Is an Email Digital Signature Certificate?

1 Star2 Stars3 Stars4 Stars5 Stars (3 votes, average: 5.00 out of 5)

Do I need an email digital signature certificate? Explore the features and benefits to make a well-informed decision!

Emails have become an integrated part of today’s society. We all use it for personal and business communications. But do you know who else loves emails? Cybercriminals! Business email compromise/email account compromise (BEC/EAC), one of the most common cybercrimes, occurs when an attacker compromises legitimate business or personal email accounts to conduct unauthorized transfers of funds. Domestic and international victims of BEC/EAC reported a total of $26,201,775,589 loss between June 2016 and July 2019, according to the FBI’s Internet Crime Complaint Center (IC3).

Emails are one of the weakest pieces of an organization’s overall cybersecurity posture, if they are not secured properly. An email digital signature certificate, such as a Sectigo email signing certificate, is one of the most efficient email security tools for organizations.

In this article, we’ll cover what you need to know about an email digital signature certificate — what it is, how it works, and what benefits it provides.

What Is an Email Digital Signature Certificate?

An email digital signature certificate, also known as email signing certificate or an S/MIME certificate, is a public key infrastructure (PKI) tool that enhances email security by enabling you to digitally sign and encrypt your emails. It uses public key encryption’s asymmetric keys to encrypt and decrypt the email messages and any attachments. As such, an email digital signature certificate secures data both while it’s in transit and at rest. With it’s hashing function, the recipient would instantly know if an email is ever altered or tampered with.

An email digital signature certificate will save you from the email threats that use eavesdropping and email spoofing — two very common email phishing techniques.

Why Do I Need Email Digital Signature Certificate?

Although an email digital signature certificate costs as little as $12.95 per year at SectigoStore.com, before investing a single penny for a new tool or technology, you always should know how it’s going to benefit your organization. Here are some features and benefits you must be aware of before making a purchase decision:

1. Asserts and Validates the Sender’s Identity

People always get confused between the personalized email signature (which works like a footer for outgoing emails) and the digital signature of the email digital signature certificate. The personalized email signature is automatically added to all outgoing messages (based on your email settings), but anyone can simply copy-paste it and tampered with it. The email digital signature certificate, on the other hand, allows you to insert a digital signature on your email, which only you can generate using your server’s private keys. This helps your email recipients authenticate you as the sender.

When an email is digitally signed, the recipients can see a small ribbon icon in the email (see the screenshot below). When the recipients click on the icon, it will show the sender’s name, email address, and original email subject. No one can change these details. This is how an email digital signature certificate gives proof of the sender’s identity. 

Email Digital Signature Certificate


  1. The sender cannot deny having sent the message. That means, no repudiation is possible.
  2. Digital signature protects the email recipients from email spoofing. No one can impersonate the business’s authentic emails.

2. Ensures Message Integrity  

An email digital signature certificate hashes and encrypts the entire contents of the email, including any attachments, along with the digital signature. Hashing means converting the data into a fixed-size string of numbers and letters using an algorithm. Each hash value is unique. So even if the sender sends the same email to the same recipient again, the hash value would be different for both the emails.

When the recipient gets the email, their server generates another hash value, which must match the hash value of the received email. Even the tiniest modification to the data being sent will result in a different hash value, which helps the recipients recognize that something is fishy about the email. The identical hash value gives assurance that the contents of the emails are intact and in the same condition as they were at the time of sending.


  1. No one can corrupt the email while it is in transit. That means, no attacker can insert malicious links, redirects, viruses, ransomware, spyware, rootkit, or any other sort of malware in the email.  
  2. The different hash value instantly warns the email recipients about the data tampering before it is too late.
  3. The business’s reputation gets ruined if a malicious email is being sent from its official email addresses. As an email digital signature certificate prevents data tampering, it indirectly plays a crucial role in protecting an organization’s reputation.

3. Protects Against Eavesdropping Attacks

With an email digital signature certificate, you can send and receive encrypted emails. Encryption means scrambling the plaintext data using a mathematical algorithm and make it incomprehensible for anyone who gets access to it. In PKI, a public key is used to encrypt the data, and only the person holding the corresponding pair of the private key can decrypt (decode) the data. When emails are encrypted, no one can read the content while it’s in transit or sitting on the server. Only the intended recipient who holds the corresponding private key can decrypt it.

Companies often use emails for internal communication. Whether or not they should, businesses frequently send and receive confidential data like trade secrets, cost and revenue information, equity and dividend related data, financial reports, etc. via emails. They also handle external stakeholders’ sensitive data such as personally identifiable information (PII), sales and purchase negotiations, recruitment-related communication with prospective candidates, etc. The consequences of leaking confidential information can be dire. But when emails are encrypted, no man-in-the-middle (MitM) attacker can decrypt and read, interpret, and steal such sensitive information when the email is in transit.


  1. It prevents eavesdropping of the company’s confidential internal communications.
  2. It prevents data leakage of the company’s communication with external stakeholders such as customers, vendors, creditors, shareholders, suppliers, etc.

According to the FBI, loss from the phishing attacks exceeded $3.5 billion in 2019. Such statistics show that an email digital signature certificate is not a luxury but a necessity these days. Plus, it’s not even expensive. You can an email singing certificate for as low as $12.95/year with SectigoStore!

Get the top-notch brand Sectigo’s email signing certificate only for $12.95/year!

Save 20% on Secure Email Certificates! Get the lowest prices on trusted email certificates from Sectigo.

Shop Now