It's a Bird, It's a Plane, It's Email Deliverability

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Courtney Sembler
Courtney Sembler



Why is HubSpot investing time (and money) into email deliverability? Is it because the name is fun to say? Is it because we want to be nerds talking with big words like deliverability? While all of that may be fun to discuss, that's not the reason.

HubSpot has dedicated time to email deliverability because it’s important for the success of your business (I know, not as fun as thinking up words that rhyme with "email").

Email deliverability seems to be the new fad of the email marketing world, with questions coming up like: how can I get into someone’s inbox? What is spam? The list could go on and on. Before we get started with the nuts and bolts of getting it right; let's define what email deliverability is.

When looking at the success of the Growth Stack model,  which was built to help growing businesses find and connect with new customers and engage with contacts. The emails they are sending are at the center. Think about trying to grow a business without having contacts. Now, imagine having customers but having no way other than picking up the phone to contact them. 

This is where you can start to see the importance of email and the even bigger importance of understanding the best tools to get into the inboxes you want.

The three biggest advantages HubSpot has implemented (so far) in 2017 with email deliverability are:

  1. Deliverability Protection
  2. Gray Mail
  3. DMARC messaging

Let’s take a look at each and find out how understanding email deliverability can help your inbound efforts. 

Deliverability Protection 

Deliverability protection is a new safeguard inside HubSpot email that protects users email reputation and deliverability by detecting and stopping sends with high bounce rates.

Deliverability protection works by first sending a portion of your email out and then paying close attention to the hard bounce rate. If the hard bounce rate is too high then HubSpot will stop sending the email before the remainder of the email goes out.  

Wait, wait, wait! What is a hard bounce? That’s a very good question. Hard bounces are bounces that indicate that the contact is ineligible to receive emails. Some examples of what would make a contact ineligible are:

  • UNKNOWN_USER - "Recipient didn't exist"
  • MAILBOX_FULL - "Recipient's mailbox was full"
  • CONTENT - "Recipient's email server rejected content" - Something in the email body or subject was a red flag that spam filters deemed spammy content.
  • SPAM - "Rejected by spam filter" - There is something in the body, subject, or from address of the email that is deemed SPAM by the recipient’s email server.
  • POLICY - "Blocked due to recipient policy" - Email servers have all sorts of security policies that your sending email address needs to pass before it accepts the message.
  • Missing category - "Unsubscribes" and "Marked as Spam" complaints are not necessarily bounces, but we will not send to these individuals again.

I will point out that this feature will only kick if the bounce rate is high so if you are doing a good job of maintaining clean lists of who you communicate with then you most likely will never see this kick-in.

This is what it will look like in HubSpot:


Up next is graymail.


Graymail is email that your contacts have opted to receive, but don't actually engage with. By reducing the amount of graymail you send, you can improve your email sending quality and score. Over time, you will see higher engagements and open rates from your contacts since you are sending to people who are more engaged in your content.

I like to think about graymail like this: have you ever gone shopping and to get the 20% discount that the store was promoting, and you filled out a piece of paper with your email on it? After this, you probably received hundreds of emails from them but never opened them. This, folks, is graymail. Mail that you opted in to receive, but don't really want.

Internet Service Providers (ISPs) learn how contacts are engaging with your emails and become better at categorizing them over time and place them in places such as the ‘Performance’ tab or ‘Low-Priority’.

Inside of a HubSpot email this is what the graymail suppression feature will look like.


Keep in mind that you control whether or not this feature is enabled by default inside of your Email Settings (Marketing to Content > Content Settings > Email).


Up next is DMARC. If you are thinking that sounds like a made up word then we are on the same page. Understanding what DMARC is however is extremely important when it comes to email deliverability. DMARC stands for Domain-based Message Authentication, Reporting and Conformance (phew, see why we say DMARC instead?)

DMARC is a way to validate the email sending domain you are sending and making sure it belongs to you. DKIM is the way to connect your email sending domain. DMARC is designed to prevent email spoofing and spam. It  is the rule to tell the system that you own the email address you are sending from.

Until recently HubSpot did not provide warnings inside of HubSpot to those who have not passed DMARC authentication.

This is what the warning sign with appear as inside of HubSpot:


DMARC authenticates the email sending domain you want to send from and there are two issues they can come across with DMARC authentication. DMARC authentication has failed due to DKIM not being set up properly and you will need recheck DKIM setup to ensure the domain is properly connected. The second is  if you are trying to authenticate gmail, yahoo, outlook, these providers do not allow this for DMARC.

Gmail changed it’s DMARC policy from p=”none” to p=”reject.” What this means is that any message sent using in the from address, will have to originate from Gmail’s infrastructure.

Now you can impress people at dinner parties by talking about DMARC validation. 

Email Deliverability in 2017 and beyond

Understanding email deliverability will be key to improving your email campaigns which will attract more contacts and bring in more revenue for your business.

HubSpot is here to help you with improving your email deliverability knowledge and implementing it in your business. 

Want to learn even more about Email Deliverability? Check out more here!

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