How It Works & Sending Encrypted Emails


E-mail encryption is the primary line of protection in opposition to cybercriminals.

E-mail is without doubt one of the most handy communication channels for companies and people, due to its accessibility. However this additionally makes electronic mail inclined to cybercriminals who try to entry delicate knowledge by intercepting emails in transit or hacking into electronic mail servers. 

One of many major strains of protection in opposition to this assault is electronic mail encryption, a broadly used approach to safe the knowledge despatched over electronic mail. 

Now, you in all probability have a flurry of questions on this matter, like:

  • What’s electronic mail encryption?
  • How do encrypted emails work? 
  • Why do you have to encrypt emails? 

Learn on to seek out the solutions to those and different frequent questions on encryption and learn the way Twilio SendGrid secures emails in transit. 

What’s electronic mail encryption?

Firstly, electronic mail encryption scrambles the content material of an electronic mail, changing it into an unreadable format known as ciphertext. As soon as an electronic mail is encrypted, solely a licensed consumer (the recipient) can decrypt it and examine the unique message.

Anybody else who tries to intercept the message will solely be capable to see the ciphertext—thus, defending the contents of the e-mail.

There are two major sorts of electronic mail encryption:

  1. Transport Layer Safety (TLS): TLS is a protocol that ensures safe communication between electronic mail servers. It encrypts the transmission of emails as they journey between servers. Whereas TLS helps safe the transmission, it doesn’t essentially shield the e-mail’s content material as soon as it reaches the recipient’s inbox.
  2. Finish-to-Finish Encryption: This technique gives a better degree of safety by encrypting the e-mail’s content material on the sender’s finish and maintaining it encrypted till it’s decrypted by the supposed recipient. No intermediaries, together with electronic mail service suppliers, can entry the content material. PGP (Fairly Good Privateness) and S/MIME (Safe/Multipurpose Web Mail Extensions) are in style protocols for end-to-end encryption.

How does electronic mail encryption work?

E-mail encryption makes use of cryptographic keys or strings of characters that exchange the unique knowledge to look random. And in contrast to the easy cryptographic keys that individuals can create, electronic mail encryption providers generate keys utilizing complicated algorithms that scramble the info past human recognition. 

So how do senders and recipients use these keys to encrypt and decrypt messages? There are 2 methods:

  • Symmetric cryptography: The sender and the recipient use a single, non-public key to encrypt and decrypt the message. This implies the sender must share the important thing with the recipient to allow them to decrypt the message. 
  • Uneven cryptography: The sender makes use of a public key to encrypt the message, then the recipient makes use of a non-public key (that solely they know) to decrypt it. That is also called public-key cryptography, and in contrast to symmetric encryption, the sender and recipient don’t have to share the important thing. 

Nevertheless, right now, probably the most broadly used sorts of encryption are likely to depend on a mix of symmetric and uneven cryptography, as we’ll talk about later. 

Why encrypt emails?

Earlier than we reply that, let’s begin with a reminder that you must by no means ship delicate info, like passwords or Social Safety numbers, over electronic mail. 

That mentioned, emails usually comprise private details about the recipient, like their tackle, or enterprise info not supposed for the general public. And with out encryption, unhealthy actors may intercept that info and use it to commit identification theft, fraud, and different crimes in opposition to people or companies. 

That is why encryption is so vital: it ensures that no particular person or entity intercepts the content material of the e-mail alongside the best way or, in some instances, because it sits in electronic mail servers. 

Moreover, as a consequence of legal guidelines just like the Basic Knowledge Safety Laws, regulators can superb companies if prospects’ private knowledge is compromised. Nevertheless, encryption may also help keep away from this. 

Lastly, encryption is a vital factor of electronic mail safety that may finally affect the sender’s fame and deliverability

Advantages of electronic mail encryption

  1. Confidentiality: E-mail encryption ensures that solely licensed events can entry and skim the e-mail content material, stopping unauthorized people from intercepting delicate info.
  2. Knowledge Privateness: E-mail encryption helps keep the privateness of private and delicate knowledge shared by way of electronic mail, defending it from potential breaches.
  3. Compliance: Many industries and areas have knowledge safety rules that require safe communication and knowledge dealing with, making electronic mail encryption important for compliance.
  4. Belief and Safety: Implementing electronic mail encryption enhances belief between events by assuring recipients that their communication is safe and guarded.

What are the several types of electronic mail encryption?

There are 3 frequent sorts of electronic mail encryption used right now. Let’s take a look at how these work, plus a safe various for sending extremely delicate info. 


Transport layer safety (TLS) is a protocol that encrypts electronic mail knowledge because it travels from the sender’s electronic mail server to the recipient’s—although it doesn’t encrypt it at its vacation spot. TLS makes use of uneven and symmetric cryptography to encrypt electronic mail knowledge. Meaning it generates and exchanges a session key via uneven cryptography, then the sender and recipient use this key to encrypt and decrypt the message.

Many electronic mail suppliers, together with SendGrid, use opportunistic TLS encryption by default (extra on this under). This prevents cybercriminals from studying the contents of an electronic mail whereas it’s in transit, often known as a man-in-the-middle assault. 

Most net servers additionally use TLS for safe looking—you may acknowledge it because the lock image on an online browser whenever you’re on a safe web site. This kind of encryption replaces its predecessor, Safe Sockets Layer (SSL).  

Subsequent, we’ll take a look at sorts of encryption that safe knowledge on the server.


Fairly Good Privateness (PGP) was the primary profitable implementation of a public-key encryption answer for electronic mail. 

Within the easiest phrases, PGP encryption works by producing a random session key that the sender encrypts utilizing the recipient’s public key. The sender then shares the encrypted session key with the recipient, who can decrypt it with their non-public key. Lastly, the recipient makes use of this session key to decrypt the message.

PGP encryption protects knowledge because it travels and on the server. This is called data-at-rest encryption or end-to-end electronic mail encryption, and it means solely the supposed recipient can decrypt the message. Thus, it protects delicate info from cybercriminals who may goal your electronic mail server.  

To make use of PGP encryption, customers sometimes have to obtain an add-on—suppliers like Outlook, Apple, and Thunderbird have PGP add-ons obtainable. Nevertheless, the sender and recipient should each set up the add-ons and allow PGP encryption to ship safe messages.


Safe/Multipurpose Web Mail Extensions (S/MIME) is a broadly used protocol for sending encrypted messages with a digital signature. Like PGP, S/MIME gives end-to-end encryption, securing messages in transit and on the e-mail server. 

This protocol additionally permits the sender to digitally signal the message, authenticating their identification and the integrity of the info they ship. So it offers the recipient peace of thoughts that the message comes from a professional sender and nobody intercepted or altered the content material alongside the best way. 

S/MIME additionally makes use of uneven encryption, requiring public keys from a certificates authority. This implies the sender makes use of the recipient’s public key to encrypt the message, then the recipient decrypts it with their non-public key. Moreover, the sender makes use of their non-public key to digitally signal the message. 

Most main electronic mail suppliers—together with Microsoft (Alternate and Outlook), Google, and Apple—assist S/MIME encryption via plugins. Nevertheless, each the sender and the recipient have to allow S/MIME encryption to ship safe messages. Moreover, directors can arrange S/MIME encryption for all the e-mail customers of their group. 

Net portal

Net portals are a safe various to make use of when you might want to share extremely delicate knowledge, resembling protected well being info or monetary info, because it’s finest to not ship that info over electronic mail. Not solely is it not definitely worth the danger of compromising the recipient’s knowledge, however rules just like the Well being Insurance coverage Portability and Accountability Act (HIPAA) usually prohibit it.

With this technique, the sender notifies the recipient by way of electronic mail that they’ve a brand new encrypted message. The recipient should then log into the safe portal to retrieve the message. This fashion, you’ll be able to nonetheless benefit from the comfort of speaking over electronic mail whereas defending the recipient’s knowledge and complying with rules like HIPAA

How do I ship an encrypted electronic mail?

Each electronic mail consumer and platform is totally different, however we’ll concentrate on how one can ship an encrypted electronic mail with Twilio SendGrid right here.

Luckily, it’s simple and automated.

Our system is configured to robotically try outbound TLS v1.1 or greater connections when sending emails. In follow, if the recipient’s electronic mail server accepts incoming TLS v1.1 or greater connections, the e-mail will likely be delivered by way of a safe TLS-encrypted connection.

Nevertheless, if the server doesn’t assist TLS, the message will likely be delivered utilizing the usual unencrypted connection.

We additionally present the choice to mandate TLS encryption throughout our electronic mail supply course of to your recipients. The Enforced TLS performance determines whether or not the recipient should assist TLS v1.1 or greater and possess a sound certificates earlier than we proceed with electronic mail supply to their tackle.

If both the require_tls or require_valid_cert parameter is enabled, the recipient have to be able to supporting TLS 1.1 or greater or possess a sound certificates. Failure to meet these standards will lead to Twilio SendGrid declining the message and producing a block occasion with the outline “TLS required however not supported.”

Safe emails in transit with Twilio SendGrid

Need to understand how Twilio SendGrid secures your messages? By default, SendGrid makes use of opportunistic TLS encryption for outbound emails. This implies we try to ship electronic mail over a TLS-encrypted connection so long as the recipient’s server accepts an inbound TLSv1.1 or greater connection. Nevertheless, if the recipient’s server doesn’t assist TLS, we ship the message unencrypted. 

It’s also possible to go for the enforced TLS setting, which lets you specify the recipient has to assist TLS. Nevertheless, in the event you select to implement TLS and the recipient’s inbox supplier doesn’t settle for the TLS encryption, we received’t ship the message. You’ll see this as a block occasion with the outline “TLS required however not supported.”

Now that you’ve a greater understanding of electronic mail encryption, study extra in regards to the different electronic mail safety elements that affect sender fame and deliverability in our 2022 E-mail Deliverability Information

Or in the event you’re prepared to begin sending safe emails with SendGrid, join free right now


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