43: There’s a domain reputation behind every email

What’s up everyone, this is part 2 of our two part episode on email deliverability and getting into the primary tab in Gmail.

If you haven’t yet, start with last week’s episode where we covered 2 crucial classification factors according to Google. The content in your email and how users interact with your emails.

Here’s today’s main takeaway: Most email marketers understand that email domain and IP reputation play a critical role in your ability to land in the inbox. But most email marketers will admit they are easily spooked by all the accompanying fancy authentication acronyms. SPF, DKIM, DMARC, they just mean allowing Gmail and other email clients to verify you as the sender. We’ll break those and many more email deliverability tips right now.

Today’s episode will cover things you can do that would help with other email clients, not just Gmail. We’ll cover sender reputation, authentication as well as tactics in your automation tool to improve deliverability. 

3. Sender rep

We know for sure that factors that influence the spam folder are also factors in the inbox vs promos tab, that’s who the email is from. There’s an IP behind the sender, but there’s a domain behind the IP.

Domain reputation vs sender ip reputation.

  • There’s two main types of email reputation that can affect your sending:
  • 1) IP Reputation and
  • 2) Domain Reputation.

Both reputation scores are calculated separately but as you’ll see as we unpack things, both scores are closely related as your sending ip is mapped to your domain.

Mailgun has a dope article on this https://www.mailgun.com/blog/domain-ip-reputation-gmail-care-more-about/ Mailgun claims that things like domain age, how the domain identifies across the web and whether it identifies with entertainment, advertising or finance industries can all impact your domain reputation. They believe domain reputation ultimately matters more to Google.

Other suspected factors by rejoiner.com

Domain reputation / Past behavior of the sender

If you’ve been sending heaving promo/spam offers through email to hundreds of thousands of people for x years, you’re bound to have a mountain of recipients that marked you as spam. So just because a subscriber is new, it doesn’t mean you start fresh. A lot of senders actually have a ton of baggage from previous sends.

Google is quite clear about this: When messages from your domain are reported as spam, future messages are more likely to be delivered to the spam folder. Over time, many spam reports can lower your domain’s reputation.

Gmail best practices

Google provides a list of best practices for sending to gmail users, it’s not overly helpful but it has some valuable tips. Aside from the obvious, don’t impersonate another company, don’t test phishing scams and make sure your domain is marked as safe, here’s 3 things Google recommends:

  1. Authentication: Allow Gmail to verify the sender by setting up reverse DNS (domain name). This means pointing your email sending IP addresses to your company domain. 
  2. Small number of sending IPs: Google recommends you stick to just 1 sending IP. They add that if you must send from multiple IPs, use different IP addresses for different types of messages. Ie; one IP for blog, subscriber emails, one for important product updates, one for upsell and promo. 
    1. I often hear email marketers say that if you are getting stuck in the promo tab, just start a fresh new sending IP. The problem there is that this is a short term benefit. If you don’t make changes to your domain, that new IP is still authenticated to the same source with the same baggage. 
    2. I have heard anecdotely that using separate sending IPs for customers vs leads greatly helps. But I know companies that don’t use this well and still have solid metrics. 
  3. Different senders: Along the same lines, Google encourages you to use a different ‘from sender’s for different types of emails and that you don’t mix different types of content in the same emails. 
    1. Ie, your purchase confirmation/new customer onboarding flow should be sent by jon@company.com and never include subscriber or promotional content. Your promotional emails should be sent from phil@company.com. So stick to as little sending IPs as possible, but switch up your sender for different types of emails. 

Domain authentication

There’s different ways of setting up authentication for your sending IPs with Gmail. The process will be slightly different depending on your hosting provider and your ESP. 

There’s currently 3 main authentication methods to prevent email spoofing; aka spammers from sending emails that appear to be from your domain:

  • SPF record (sender policy framework)
  • DKIM keys (DomainKeys Identified Mail) 
  • DMARC record (Domain-based Message Authentication, Reporting, and Conformance)


Publish an SPF record for your domain.
AKA Pointer (PTR) record. Every SPF has a single TXT file that specifies servers and domains that are allowed to send on behalf of your domain. You do this by uploading your updated TXT file on your domain provider settings.


Turn on DKIM signing for your messages.

DKIM lets a company take ownership of an email. This is why the reputation of your company domain (not your sending IP) is the basis for evaluating whether to trust the message for further handling, such as delivery.

DKIM uses a pair of cryptographic keys, one private and one public. A private key aka the secret signature is added to the header of all your emails. A matching public key is added to your DNS record. Email servers that receive your messages use the public key to decrypt the private key in your signature. That’s how they verify the message was not changed after it was sent.

Google has a simple guide for doing this, you start by generating a key for your domain, and just like your SPF record, you add the key to your domain’s DNS records.


Publish a DMARC record for your domain. DMARC is used in combo with SPF and DKIM, should be setup after.

Specifically helps you prevent spoofing, aka a message that appears to be from your company but is not.

It checks whether the From: header matches the sending domain in your SPF/DKIM check.

Once you start sending after DMARC is setup, you can start to access reports from email servers that help you identify possible authentication issues and malicious activity.

Google has a nifty recommended DMARC rollout which encourages you to start with a none policy so you can view reports before you start being more restrictive.

Eventually you can grow to a quarantine policy which basically puts messages in Spam for your recipients. The strictess policy is reject, in this case messages aren’t sent to spam, they never reach the recipient.

Postmaster tools

Get detailed information about your IP and domain’s reputation with Postmaster Tools.
You can use PT to get data on large email sends from your sending domain.

Google gives you a dashboard with data on:Spam rate: % of emails marked as spam vs. went to inboxSending IP reputation: better rep = better chances of landing in inbox
Domain reputation

So, what is a good sender score? You want to be as close to 100 as possible. But you definitely want to keep your domain reputation above 70.

*Google says: Tip: Keep in mind that spam filtering is based on thousands of signals, and IP reputation is just one of them.*

4. What you can do in your ESP

Send to engaged subscribers only

Use double opt in
Be upfront about what and how often you’ll send
Auto suppress disengaged people

Keep your list clean

Have data hygiene programs that look for things like invalid emails, fake emails, catch-all emails, disposable emails

Consistency and warming up a new sending IP

One thing Google notes as important is to increase your sending volume slowly. If you have a big list and you send many emails, it’s important to send a consistent amount of emails rather than having big spikes/bursts. 

So to recap:

  • Companies should not focus on getting out of the promos tab and into the primary inbox
  • The focus should be on providing valuable content that your subscribers enjoy reading and engaging with, we covered a bunch of ways you can help get into the right inbox
  • How? Use as little HTML as possible. Write like a person to a person. 
  • Limit the promo words you use in your copy
  • Reply to the email seems the best way to get users to tell gmail that you are legit and you deserve to be in the main inbox
  • There’s an IP behind the sender, but there’s a domain behind the IP, understanding sending reputation will help you as an email marketer.
  • There’s currently 3 main authentication methods and they aren’t as scary as they sound, learn the basics and know how to talk to your IT team about them
  • Get detailed information about your IP and domain’s reputation with Postmaster Tools.
  • Send to engaged subscribers only and keep your lists super clean yo


Intro music by Wowa via Unminus
Cover art created with help via Undraw

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