SPF vs DKIM vs DMARC. Why Are They Important?

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Email deliverability has never been as important as it is today.

To protect users, email servers employ a variety of authentication methods to ensure that no spam or malware emails enter inboxes.

But they’re not always the best at it.

For salespeople, this means that sometimes that perfectly crafted and relevant cold email may not make it through due to technicalities.

To avoid ending up in your prospect’s spam, one thing you need to do is make sure that your email is authenticated as well.

And there are three ways you can do this.

What Is SPF

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The first method is Sender Policy Framework (SPF).

Having this set up and authenticated properly, controls the list of authorized IP addresses that send emails on your behalf.

It helps you avoid spammers or other users spoofing your domain.

This means they cannot make up a new email address and send spam or malware on behalf of your domain.

You kill two birds with one stone: you’re protecting your domain and helping your prospect’s domain identify your domain as trustworthy.

Advantages of SPF

Having SPF as your authentication method has several advantages:
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SPF, at its basic level, serves to authenticate your email.

It does this by ensuring that there is a record of your email domain that your prospect’s domain can check against. This provides your domain and address credibility when interacting with other domains and servers.

Of course, this leads to an overall improvement in your email reputation.

The email servers of your prospects then judge you as trustworthy, and as an email that is secure enough to make it through the spam filter.

On your end, as a user, it also helps to protect your email inbox from malicious emails and similar, identifying them as such and flagging them as spam.

There are some disadvantages, however, namely that your IP address is not part of the record, which can still send you to spam. It is also considered not to be strong enough on its own to prevent anti-spoofing and works best when in conjunction with the DKIM and DMARC authentication methods.

What Is DKIM

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DKIM stands for Domain Keys Identified Mail. An apt name, as it makes use of public-key cryptography instead of IP addresses.

The authentication in this case is based on the use of a digital signature in the email headers of all outgoing emails. These are then validated using the public cryptographic key found in the company’s DNS records.

Companies must have both private and public keys added as a TXT record, as this is what your prospect’s emails will use to verify you are not spam.

Email servers and ISPs validate the email signature by decoding and comparing the public and private keys: for the email to go through, the values have to match.

Advantages of DKIM

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The first noteworthy advantage of DKIM is that it’s a stronger form of authentication than SPF, as it relies on encryption methodology.

It is also a good way to avoid losing information. The digital signature is part of the email header, which means it is not lost if the email is forwarded. This means your method of authentication remains visible and consistent every time it gets sent to someone else.

SPF, unfortunately, is added as additional information to the message envelope, and this can be lost via forwarding, causing the email to potentially end up in spam.

Another positive of DKIM is that, while it does not filter or identify spam, it does prevent spammers from changing the source addresses of your message. It furthers the anti-spoofing system.

Neither SPF or DKIM, however, have a way to offer instructions to email servers and ISPs on how to treat an incoming message if the authentication checks cannot be verified satisfactorily.

Enter DMARC.


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Domain-based Message Authentication, Reporting and Conformance (DMARC) is the final email authentication method we will cover today.

Its main purpose is to help mail administrators prevent hacking or spamming by outsiders pretending to be emailing from your domain.

Fairly similar to the two previously mentioned methods – in fact, it makes use of the two previous methods to work. And it provides mail systems with assistance when it comes to figuring out what to do with emails that do not pass the verification process.

It does this by allowing the domain owner to decide and specify how they want their inbox filter to handle messages that cannot be authenticated via pre-defined policies. Typically, they go from rejection or bounce, to spam, to simply allowing it in.

Whoever sent the email also receives a report of what happened, which is good as it can provide them with insight into why they are not receiving responses.

Overall, following this protocol is heavily recommended.

To have DMARC set up properly, you need both the SPF IP address and the DKIM signature to be working. Your domain thus demonstrates to other ISPs that you are an actual sender, not a spammer, who is taking precautions on your end to protect your identity and IP and sender reputation.

In turn, this increases your likelihood of ending up in your prospect’s inbox and avoiding the spam filter trap.

Advantages of DMARC

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Of the three, DMARC has the most advantages as it takes on the same qualities of the two previous methods and adds additional benefits.

These include:

Receiving and sending reports about the email messages you’ve sent, so you can know if they end up being bounced back or sent to spam and can adjust accordingly. It also makes your email domain read as genuine and valid.

You are demonstrating that you care enough to control your steam of emails and how your are identifying yourself as a sender. This increases trust from other ISPs and adds value to your emails over those of others.

And of course, it makes it easy and quick for your prospect’s domains and servers to identify your email and verify it as trustworthy.

The only drawback is that, occasionally, it is possible that a legitimate email ends up being misplaced as spam, but it is better to be protected both for yourself and for your prospects and sales goals.

To have a clearer idea and understanding of how they each differ, let’s compare a bit, so you can weigh the pros and cons of each method yourself:
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Without SPF, there is no DMARC.

If you can only do one of the three, SPF is by far the easiest to have ready. However, it can cause issues as it is not as perfect without DMARC.

DMARC uses both SPF and DKIM to validate email addresses, making it a lot faster and more trustworthy to your prospect’s servers when receiving emails. You can also lose this validity with SPF if it is forwarded.

And you are losing out on more responses if you only have SPF and an email fails to be verified by a prospect’s inbox.

DMARC provides a reporting system that helps those receiving your emails take certain actions if for some reason your messages do not pass the verification requirements.


There are two main differences between the two:

First, SPF relies on IP addresses for anti-spoofing and determining which addresses can send mail from a particular domain. DKIM’s approach is more sophisticated and safe, as it instead relies on an encryption algorithm to create electronic keys that are tied to a digital signature.

Second, DKIM uses the signature to validate trust. Because this information is found in the header, it is preserved when forwarding. SPF, instead, will lose the information tied to its trustworthiness when forwarding, as it is found in the message envelope.

While both methods can work independently of each other, it is best when used together to make up for each other’s flaws.


The comparison between DMARC and DKIM is similar to SPF and DMARC.

DMARC needs both DKIM and SPF to work, while neither of them need something else to be set up previously.

But because DMARC makes use of both authentication methods, your prospect’s inboxes are far more likely to accept your emails a lot quicker as it is a faster verification process.

What DMARC does offer that neither DKIM nor SPF do is the possibility of your prospect’s inbox to decide what to do with your email if for some reason it fails the verification checks.

Based on what your prospect’s DNS settings look like, there is a far greater chance that your email will still make it through. After all, if you have taken the time to make your email safe and secure yourself, it means you send safe and secure messages that are good to receive.

How to Check If SPF, DKIM and DMARC Are Set?

Having gone through why you want each of these to be set up properly, you’re probably wondering – how do I even check for that?

As salespeople, the technicalities of email deliverability may initially seem to be the territory of IT. It’s all very technical and complicated, and there might be code involved.

This is not the case.

In fact, in our experience with clients, IT departments are usually just as in the dark about email deliverability as folks in HR.

It is the territory of sales and marketing to ensure that their messaging is getting to prospects or leads. And it is actually a lot easier than you might think to both set them up and check that they are set up.

Warm’s main purpose is to help you warm up your email so that your email deliverability remains positive, and your cold emails are landing in your prospect’s inboxes safely. It does this by generating conversations so that your email domain does not read as a spammer that only sends messages out.

Because we care about all aspects of email deliverability, we have created a free SPF / DKIM / DMARC Checker. Instead of paying a subscription fee for an external service, simply follow the steps on the video below the tool and copy-paste your content to make sure your email domain is ready to send!


Email deliverability is the concern of sales and marketing, not IT.

As such, it is up to us as salespeople and marketing professionals to check that our emails are set up correctly to arrive at our prospect’s inboxes.

Having your DNS settings prepared and verified is an essential step in this process. This article has outlined the three authentication methods you can take to make this happen, although using the three together is by far the most successful.

Tools such as Warm also help improve your sender and IP reputation – why not join our waitlist as we continue to create tools for salespeople, by salespeople?
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