MTA-STS email security

What is MTA-STS and why do you need it to improve email security?

email security
DMARC Report
What is MTA-STS and why do you need it to improve email security?
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There has been a lot of talk about how your outgoing emails should meet certain parameters (like the sending domain should be authenticated), but what about the incoming emails? If an email is not properly secured during transmission, it is susceptible to interception or tampering, which, if successfully implemented, can wreak havoc on your digital infrastructure

So, to ensure that all the emails that come into your mailbox are safe and free of any malicious breach, you need a robust strategy, and Mail Transfer Agent Strict Transport Security (MTA-STS) does the job. Just like SPF, DKIM, and DMARC, MTA-STS is a security protocol that secures emails sent to your domain and prevents attackers from exploiting a weakness in standard SMTP (Simple Mail Transfer Protocol) security. It works on various levels, like ensuring all of your email servers use Transport Layer Security (TLS), have valid publicly trusted certificates, a published DNS record, and a TXT file to keep impostors at bay. 

Let us dig further into this email security standard and understand why it should be an integral part of your security strategy:

mail transfer agents

What is MTA-STS?

Back in 1982, when SMTP was first introduced, it did not include any security mechanisms in order to protect communications between mail transfer agents. This loophole was leveraged by interceptors to tamper with the email and execute their malicious intentions. To tackle this situation, a new command was added to the SMTP— STARTTLS, which allowed for the conversion of a non-secure connection into a secure one using TLS. Despite this measure, there was still room for improvement, which led to the introduction of MTA-STS

Now that we know how MTA-STS came into being, let us understand what this security standard is all about.

As per the policy specified in RFC 8461 MTA-STS lets you add a layer of security between the sending and the receiving server. It does so by ensuring that emails are transmitted over an encrypted connection via TLS. Once you implement MTA-STS, you inform the senders that your receiving servers only accept emails sent through SMTP over TLS instead of an insecure SMTP connection. 

By simply adopting this security protocol and letting the sender know that you prioritize encryption for your incoming emails (along with outgoing), you can mitigate the risk of grave cybersecurity threats like man-in-the-middle (MITM) attacks. 

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Moreover, as MTA-STS helps ensure that only legitimate servers with valid, publicly trusted certificates can send emails to your domain, you can rest assured that emails arriving in your mailbox do not bring along any potential security risks

Why was MTA-STS introduced?

As you already know, MTA-STS was introduced to fill in the gaps left by the STARTTLS protocol, but what exactly is the problem that this new security standard solves? 

The primary issue with traditional SMTP was that it did not make encryption mandatory, even with the STARTTLS command. 

Undeniably, this command worked as a reliable defense against certain attacks, but they were mostly passive attacks. When it came to active network or man-in-the-middle (MITM) attacks, the command fell short. It made way for the attackers to intercept the connection and surpass the STARTTLS upgrade, making it seem like the receiving server (also the target) did not support encryption. Additionally, attackers could intercept DNS queries and respond to MX queries with a list of attacker-controlled email servers. In this case, the messages sent by the sending server would be directed towards the attacker’s server, as it uses encryption to appear legitimate.

Man-in-the Middle (MITM) Attacks

Image sourced from fortinet.com

MTA-STS solves these problems by doing two things:

  • Allowing domains to enforce the use of strong encryption (TLS) for email transmission.
  • Ensuring that domains can securely specify which mail servers (MX servers) should receive their emails.

Why should you implement MTA-STS?

MTA-STS does not just patch the loopholes in SMTP but also helps enhance the overall security of your email communications. Here’s how:

Preventing man-in-the-middle attacks

If there is no MTA-STS in place, emails sent to your domain can get delivered over unencrypted connections. This means that they would be extremely vulnerable to interception or even modification by attackers. But with MTA-STS, you don’t have to worry about any of it, as your emails will only be delivered along safe, encrypted channels, bringing this risk down to a great extent.

Enhancing email privacy

By requiring encryption, MTA-STS helps protect the contents of emails from being read by unauthorized parties during transmission. This is a non-negotiable, especially when it comes to maintaining the confidentiality of sensitive information shared via email.

Building trust with senders

Implementing MTA-STS is an indicator that your organization is seriously concerned about email security, which enhances confidence among those who exchange emails with you. In other words, it reassures senders that their messages will be delivered securely to your domain.

email security

Compliance with security standards

One of the primary compliance requirements of most organizations is data protection and privacy, and MTA-STS can help you achieve it. By enforcing encryption for all incoming emails, MTA-STS ensures that sensitive information remains secure during transit, preventing unauthorized access and tampering. This is a non-negotiable aspect for industries that handle highly confidential data and are subject to strict regulatory standards, such as finance, healthcare, and legal services.

What’s next?

It is safe to say that cybersecurity is a two-way street; that is, your incoming emails should be as secure as the outgoing ones. Essentially, this means that both ends of the communication channel should be fortified and have a strong defense mechanism against cyberattacks. One way to do so is by implementing MTA-STS along with DMARC. By pairing the two security mechanisms, you not only ensure that your entire email channel is protected but also boost your email deliverability

Are you ready to protect your digital infrastructure from evolving cyber threats but not sure where to start? Our team at DMARCReport will help you embark on your email security journey by offering detailed insights and expert recommendations to improve and further develop your security strategies. Book your demo with us today! 

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