There are several things to understand about the construction of email, headers, and domains. Multiplicity and mixture of official and casual wording, names, and references can be confusing and misunderstood even by professionals. Let’s dive a bit into the details of the structures of email to see if it’s as hard to comprehend as it might appear at the first glance. In this article, I will cover the subject of domain alignment.
What is domain alignment? Alignment in domain terms is simply a sameness of the identity of domains included in the email construct - both headers and the body of the message. The identity might be looked at as the “second level” of the domain, so anything that comes before .com, .org, etc. It might go “deeper” as well (so more to the left) - the third or even fourth level: like example.of.yourdomain.com. In this regard, we distinguish two types of alignment, strict and relaxed. - Strict: This type of conservative alignment concerns any type of showing domains that are exactly the same, and exactly at the same “level”. As an example, we can look at the email address: you@yourdomain.com and the URL - www.yourdomain.com. Those two are aligned in a strict manner. But if your FROM address would be you@mailer.yourdomain.com, to achieve strict alignment, the URL would need to be www.mailer.yourdomain.com. Same level, the same subdomain’s suffix. - Relaxed: A more liberal mode of aligning allows a subdomain from a parent domain to be compared with a different subdomain or the parent domain itself - you@mailer.yourdomain.com is aligned relaxed with www.yourdomain.com. In the same way, you@mailer.yourdomain.com and yourmom@yourmom.yourdomain.com are also “relaxly” aligned. It’s worth noticing, that it works from left to right. So yourdomain.com and yourdomain.net will never be properly aligned even though the NAME of the second level is the same. Those are so-called “cousin” domains and are separate entities.
Is it important to have domains aligned in email marketing? I bet it is easy to guess that since this article was written there is some importance in the subject. It happens to be, however, easily overlooked and often undervalued. How come? The recipients' filters and firewalls are battling millions of spam every day, separating the wheat from the chaff. This requires heavy computing power, and that means costs. Each new entity such as a domain showing up in the single message means additional checks, cross-references, and lookups. And that comes with additional calculations and more energy consumed. Therefore, most Mailbox Providers (MBPs) value simplicity, clarity, and homogeneity when it comes to email structure. Moreover, a sender can expect much “smoother” treatment when he's being transparent about who he is, and what he brings to the table.
On the other hand, a marketing email creation nowadays uses so many different tools, hostings, and creators that it’s easy to get lost in the multiplicity of addresses and URLs showing up in the final email. Let’s look more closely at some important elements of the email construct, as an example taking two email headers.
Headers
RFC5321 header called “Mail From” is not the same as the RFC5322 header “From” (also known as “Friendly From”). Pretty clear, no?
I know it might be confusing. Actually, those two email addresses (contained in the respect headers) that might seem to point to the same entity (the address that the message actually came from), are separate beings. For a better understanding of the difference, imagine you receive a letter from your mom. The letter comes in an envelope, and it is signed. The envelope has a name and the sender's address for eventual return purposes (for example, if you don’t pick up the mail in time or move away from your house). The envelope in this example would be signed with the Mail From address. It says, who is the carrying (delivering) entity and to whom return the mail if the delivery fails. Looking at it this way it’s easier to understand why the “Mail From” header is often called “Envelope-From” as well.
Now, if you take out the letter from the envelope and read the millions of letters your mom has sent you, there’s an additional signature - “lots of hugs and kisses, Mom”. That would be the Friendly From - for example, the name or surname of the author of the letter. This can be a totally different sender than the Mail From (envelope), and in the case of a third party sending (like an Email Service Provider) - it very often is.
Another example of such a difference can be when you receive an email from your bank. The “Envelope From” header will be containing the address of the bank itself (offers@mailer.yourbank.com), however, the “Friendly From” will be the signature of Mr. Paul, who is your personal accountant - for example, “mrpaul@yourbank.com”. It’s worth adding, that the “Friendly From” header can also be appended with an additional text field - for example, <“Mr. Paul” mrpaul@yourbank.com>
Why is it important? It’s a bit technical, but also partially a branding thing. The “Friendly From” is the address that is visible to the recipient as the actual sender of the message -
Whereas RFC5321 “Mail From” header is a more technical address. That is the first one that shows up in the SMTP dialog and is most often used for sending remote bounces if any occur after the sending process is over. This is hardly ever visible to the recipient who is not specifically interested in seeing it.
It is allowed for these addresses to be different, and in the world of shared infrastructures and environments, it is, actually, quite common. A very important part here is to properly authenticate such messages - each domain appearing in either of those addresses should be properly signed with a DKIM signature.
DKIM domain
DKIM signature is like a hand signature of the author of the message, represented by a specific domain. This domain is highlighted in the DKIM-related headers (specifically in the d= or I= flags). There can be multiple such signatures, if there is a need - in our case, whenever it’s unavoidable to use addresses with not aligned domains, we can add multiple DKIM signatures, for each domain in the “From” or “Mail From” addresses. This way we are assuring the recipient, that all the entities involved in creating and sending the messages are taking responsibility for the message. At the same time, it’s close to certain that the message was not tampered with or abused on the way to the recipient. Using our previous example, we are assuring nobody is signing as your mom just to fool you for any malicious purposes. To learn more about DKIM, you can refer to our Authentication Articles.
URLs & images
Many platforms offer an option for custom link tracking; this allows you to have your domain visible in the links placed in the message. Normally, a click tracker is hosted by an ESP and its domain would be displayed in the mailbox; setting up a custom link-tracking domain solves this issue and gets you the alignment we’re after. And that means increased trustworthiness (the filters will recognize your sending domain in the URLs), more control over your domain’s reputation, and improved brand recognition.
At all times, we should be aiming for a complete alignment for all the domain-related entities (headers, email addresses, URLs… ) in the message. However, it is likely that 100% of alignment is not possible for various reasons, such as tooling limitations, complex sending infrastructure, and so forth. However, the upsides of such unification are enticing enough to have a strong consideration for getting as close to 100% as possible. As mentioned above, additional DKIM signatures are able to help us with giving additional domains appearing in our messages more trust and reputation control.
So whenever you are in doubt about whether the alignment is or isn’t achieved in your mail, please contact your IT department or your current Email Service Provider. This should be easily checked in the sent test email's source. Maybe the URLs are not aligned with the “From” header. Or maybe some of the headers are not in alignment with each other. This should be addressed with changes in the mail structure itself if possible, or with additional DKIM signatures as mentioned above. In both cases, your IT department working with your ESP should be helpful. Mailkit will help you out with achieving full alignment from scratch, which is essential and heavily time-saving. Our support team will guide you through all the processes necessary to get there and monitor the email flow after.
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