Deliverability: How to correctly deliver your newsletter to your contacts in Email Marketing

After almost 50 years since its inception, despite (as with other areas of web marketing such as the SEO) if it periodically decrees its "death" and despite the fact that over the years have emerged forms of messaging with higher open rates such as Messenger or WhatsApp, according to a Litmus statistics, email marketing, is still able to generate a higher ROI of any marketing communications channel, equal to $ 42 returned for every dollar spent.

But in order to generate a return on investment you need to make sure that the newsletters you send out reach their destination first: we're talking about deliverability or rate of deliveryone of the most underestimated KPIs of theemail marketing and which constitutes the first step of the "funnel" of email marketing, of which you can find an image below.

How much money are you leaving on the table from non-delivery of emails?

An email, before it can even be clicked on and generate a conversion, has to be opened, but to be opened it has to arrive in the inbox of the recipient's client: this means that having deliverability issues has a direct impact on the (failed) return on investment you can get from your email marketing initiatives.

What is Email Deliverability?

Email deliverability is the process of sending email to the recipient's inbox without it being directed to the spam folder, blocked by the recipient's inbox provider, or generating a bounce, i.e. a soft or hard bounce.

In this nice infographic by here is explained the journey of an email from sending it from your Email Service Provider until the coveted arrival (or non-arrival) in the inbox of your lead, prospect or customer:

email marketing deliverability
Source :

How does an email get delivered to a recipient?

To understand how the delivery process takes place and what possibly hinders it, let's make a premise: an inbox provider, i.e. inbox providers like Gmail, Yahoo, Outlook, Hotmail, scan the content of incoming mails with the aim of filtering spam and preventing pishing or unwanted mails.

The last Returnpath Email Delivery Benchmark Report analyzed over 2 billion email messages sent in 2019, and here's what they found: the overall inbox delivery rate is about 85%, which means that about 15% of emails worldwide never reach recipients' inboxes.

average email marketing deliverability rates

EmailToolTester has explored the topic of Email marketing delivery in different ESPs since 2017 According to this study, the average deliverability is 88.9% and 11.1% of emails are missing or caught by spam filters.

As you can see the delivery rates were analyzed at different email service providers such as:

Sender Reputation and Deliverability

In the scanning process, the reputation of the sender is assessed, which then ensures effective delivery. Deliverability is largely determined by the reputation of your sender: the better your reputation, the more likely it is that your email will be delivered to the recipient's inbox.

By what is sender reputation determined? By a wide variety of factors, including:

  • Recipient Engagement to Your Emails: When your recipients open, read and click on your messages, your inbox providers know your messages are wanted;
  • Email Content;
  • Any spam complaints;
  • Spam traps;
  • Invalid email addresses (and thus what is called lyst hygiene);
  • Black List;
  • Reputation of the sender's domain.

The reputation of the sender, as it happens in the real world, is built over time and is not immutable: in any case there are also software tools to understand the reputation of a sender.

Here's what can block the delivery of an email:

Let's take a closer look at the above factors that impact deliverability.

Email Engagment and Deliverability

There are various types of involvement on an incoming email, positive and negative: depending on your inbox provider, you could keep track of how many times a message is: forwarded, ignored, deleted without being opened, moved to another folder.

Or, if your email campaigns are getting very low open rates, inbox providers may start filtering your future emails as spam because your recipients indicate that the email is unwanted. Or, if you're getting high unsubscribe rates, inbox providers may read this as another signal that you're sending unwanted mail.

Spam complaints

A recipient marking your email as spam is the strongest negative signal to inbox providers. Spam complaint rates higher than 0.1% / 0.2% are considered high. And these levels can lead to worse delivery rates. After sending an email marketing campaign you can always keep an eye on your spam complaints.

Spam Traps

The "spam traps" are old or unused email addresses that should not receive your emails, also used by ISPs and anti-spam organizations to identify spammers. The presence of spam traps in your contact list is a sign that your list is not well edited. One way to avoid spam traps is to:

  • remove recipients who no longer interact with your emails, then members who have been inactive for 6 months, for example;
  • avoid buying, renting or stealing email addresses, as those recipients will either not collect engagement or report you as spam;
  • acquire email addresses in a lawful and consensual manner, with strategies of Lead Generation and validate them as Double Optins.

Invalid email addresses

Continuing to send emails to invalid or non-existent addresses can damage your reputation: in fact ESPs, or email marketing software when an email no longer exists mark it as hard bounce and put it on a black list preventing its subsequent use.


Many inbox providers monitor blacklists to help determine which senders should be blocked or filtered. Most blacklists will list your sending IP address or domain if they detect a high number of spam traps, spam complaints.

Here's a blacklist:

Just because you're blacklisted doesn't necessarily mean your deliverability will suffer. Some blacklists have a much greater impact on deliverability than others. If you're interested in seeing whether or not you've been blacklisted, MXToolBox allows you to check it for free.

Reputation of IP and sender domain

When you send a newsletter with your Email Service Provider, you may do so with a shared or dedicated IP and a related sender domain. Both are associated with a reputation.

All email is delivered via an IP address. Inbox providers use your IP address to evaluate your sending reputation when determining whether or not to send your email to the recipient's inbox.

Dedicated IP or shared IP?

If you're a high volume sender (over 3000 emails per month according to SendinBlue) and you want to be in control of your sending reputation, you can equip yourself with a dedicated IP address.

If you are sending email over a new IP address, a recommended practice is to "warm up" your IP appropriately by sending low volumes of email over your new dedicated IP and then gradually increasing the volume over time to provide Internet Service Providers (ISPs) time to recognize, identify and evaluate your sending practices.

Sharing an IP address can be a great solution if you're a low-volume sender: if the cohort of senders you belong to follows best practices, you may have a reliable IP address.

IP segmentation

Sharing a main domain between emails of various types, transactional, automation will merge reputations into each other. A classic case is marketing and transactional emails that often have very different reputations: it may be appropriate to separate traffic by IP by type. In this regard, win back campaigns with naturally lower than average engagement rates should (ideally) have a different IP.

Did you like this article? Share it!

Other articles on the subject that might interest you:

Consultancy and training courses on Lead Generation, Marketing Automation and Performance Marketing

Do you want to increase the quantity of potential customer contacts, improve contact quality, reduce the cost of lead acquisition, turn contacts into paying customers and increase their value over time?


Shall we have a chat?

Contact me: