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Inbox placement through the lens of a marketer

A marketer's gear

When you Google “how do I land my emails in inbox,” you’ll find close to 195,000,000 results.

While this doesn’t come as a surprise considering the longevity of email marketing, it certainly testifies to one thing: Email deliverability (inbox placement) is arguably the most-discussed topic in email marketing. This is because the process equally involves the email marketer, email marketing platform, and the Inbox Service Providers. And the resulting area of intersection is a bit challenging to understand while starting off.

Participants of email marketing process

In our recently concluded webinar, we set out to explain email deliverability in simple terms.


Here’s the rundown of the conversations we had during the webinar. For those of you who prefer reading, we decided to summarize the webinar’s key takeaways below.

Key terms 

ESP – Email Service Providers (for example, Zoho Campaigns)

ISP – Inbox Service Providers, aka mailbox providers (for example, Gmail)

Email-sending domain – Your own domain associated with the email marketing platform (for example, 

Lookup site A site that provides crucial information about a domain in an easy-to-understand way

DNS – Domain Name System

User scenario

Alex is a marketer trying to reboot email marketing for his company, Zylker. He’s signed up for an email marketing platform and is going to send his first email campaign as per the user manual.

Your takeaway

Alex’s first email campaign will help you learn three aspects:

  • The role of anti-spam services and Inbox Service Providers in email marketing
  • The whys and hows of configuring your email marketing software
  • The specifics of content creation and mailing list management

In summary, you’ll learn what happens after you hit an email’s send button and how to put the best foot forward to achieve inbox placement.

Step one: Studying the domain’s reputation

Before associating his domain with the email marketing software, Alex wants to ensure that it’s not in the bad books of anti-spam services. To check this, he turns to one of the lookup sites.


Anti-spam services create and maintain blacklist(s), online registries of domains and IP addresses that were used to send any form of spam. Some of the mailbox providers likely join forces with anti-spam services to strengthen their security system. This way, they accurately prevent an incoming email with blacklisted domains and IPs from reaching the mailboxes.

The image below shows how Spamhaus—one of the prominent anti-spam services—contribute to email security.

Spamhaus and ISPs

Source: Spamhaus

While these services use different under-the-radar techniques to maintain blacklists, the usage of spam traps is widely known.

Step two: Associating the domain

After knowing the domain is in the good books of anti-spam services, Alex creates a subdomain to easily narrow down email-deliverability problems in the future and safeguard the reputation

Difference between domain and subdomain


When you use your primary (or parent) domain for several purposes, there’s no room for error at all. A non-email-marketing problem hurting your domain’s reputation has a bearing on your email marketing and vice versa. This is where subdomains come into play; they help you identify email-deliverability-based problems with a macroscope instead of a microscope. The best part? It works as a separate domain while still being connected to your primary domain.

Step three: Authenticating the domain

Now Alex has to prove that he’s a safe and authenticated sender in the eyes of mailbox providers (because of rising spam activities). To achieve this, he uses two mechanisms prescribed by his ESP: Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM). He copies the SPF and DKIM records exclusively generated by his ESP and pastes them in the TXT record of his domain’s DNS.

Domain authentication


Since your emails are always bypassed via the servers of your ESP, their domains and IPs also enter the picture. Therefore, the mail servers of your recipients ask a question to your ESP: “How can we ascertain that this email is actually from the concerned sender?” This is when the SPF and DKIM mechanisms come in handy.

With the SPF record, the ESP will hint the domain and IPs assigned for your account. (They also communicate to the mailbox providers the entire set of domains and IPs used by them.) By publishing the SPF record on your DNS, you validate your email’s point of origin.

SPF flowchart

With the DKIM record, a unique alphanumeric key is assigned to your account. So every time you send an email, an encrypted code along with a special header is added to it by the ESP. The code is then decrypted by your recipients’ mail servers using the key present in your DNS, thereby again validating the email’s point of origin and, most importantly, ruling out any possibilities of foul play in transit.

DKIM flowchart

Step four: Crafting content

With the account set up, Alex is now raring to use the creative freedom that ready-made email templates offer. He heads over to the template editor and customizes the template, ensuring that his email is a combination of plain text, image, and, most importantly, (healthy) URLs.


The ultimate goal of every email marketer is this: creating content that persuades their audience to complete the end action. The scoring system of mailbox providers—which is used to gauge your email-sending domain’s reputation—is also in line with that.

The way your recipients react to your email generates positive and negative scores. If someone clicks your links (preferably and visibly embedded as CTA buttons or hyperlinks), you garner the highest-possible score. However, if your score declines below the cut-off range, your domain gets blacklisted.

Scoring system of ISPs

Now comes a question: What if you’re using a brand-new domain that has a zero reputation? Simple! Warm up your domain. Start off with low-volume emails, build a positive reputation, and go through the gears.

Step four: Selecting the recipients

Since Alex is resuming email marketing for Zylker after a hiatus, he wants to know how healthy the current mailing lists are. For this, he turns to the analytics of the previous campaigns.

Subsequently, he segments the database into three based on receptiveness: inactive contacts, partly active contacts, and highly active contacts. Finally, he overlooks the inactive contacts and associates the other two segments for this campaign.


Continuously sending emails to (highly) inactive contacts can affect your domain’s reputation in the long run. Furthermore, if a contact doesn’t access their mailbox for a very long time, the ISPs convert the email address into a spam trap. (This is called recycled spam traps, and the cut-off time before the email address is converted into a spam trap varies from one ISP to another.) If an email is sent to such spam traps, it takes a huge toll on your reputation.

Inactivity period set by ISPs


Note: Like anti-spam services, the ISPs also generate pure spam traps (fake email addresses) and disseminate them on the internet, presuming spammers will use or sell them in the dark-web marketplaces. From there, it’s only a matter of time before it reaches email marketers who’re looking to purchase mailing lists. Here’s an extensive guide on spam traps and how to avoid them.


Alex is set to push the send button now. And, like most email marketers, he can’t wait to come back and check the analytics so he can sharpen his next campaign.

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