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How to optimize your email deliverability
How to optimize your email deliverability

Email blasting is a key tool for any organization. This HOWTO will outline ways in which you can optimize your email deliverability.

Updated over a week ago

📌 Note: A/B testing is available as an add-on. For more information on adding new features please see the add-ons page in your nation.

Table of Contents

Main principles

Email deliverability is the metric of your email campaign’s success. It is rated by how many of your emails reach your supporters’ inboxes. The metric is affected by many factors, including:

  • Spam reports

  • Bounced & bad emails

  • Clicks & opens

Think of your email deliverability as a reputation. If recipients engage with your emails, you will gain a reputation as a good sender and providers will ensure your email gets to the right inbox.

Any indication that your email is spam-like will be carefully observed by email providers and tarnish your reputation. As your reputation is affected, email providers will limit your emails from being delivered, sending your messages to recipients' junk folders, or blocking messages from your email address entirely.

📌 Note: NationBuilder monitors your email deliverability and limits the total number of recipients for your email blasts to protect your reputation. If you are consistently receiving good engagement on blasts near your current limit, contact us to request a limit increase.
This monitoring will also pause your email capabilities if you are in danger of damaging your reputation. Employing good deliverability practices, like those covered in this article, will help avoid disruption to your email service.

Every provider has their own formula for determining if an email is spam, which is not publicly shared. While there is no way to know exactly how to avoid their criteria, following the best practices listed here will help protect your deliverability across providers.

There is also a clear strategic advantage to keeping your email deliverability high – an engaged email list is capable of more action: they donate more, they volunteer more, and they are more responsive to the asks you make of them.

There are a few main principles to consider when building your email deliverability practices:

1. Consent is crucial: You need to have your supporters' permission to send emails in the frequency and subject desired. Having consent means that your supporters have an expectation to hear from you. This ensures that few people will feel the need to unsubscribe or mark your emails as spam.

2. Quality over quantity: It is better to have an engaged list of one thousand people than an apathetic list of ten thousand. Over time, people who remain un-engaged on your list will damage your reputation and prevent emails from getting to those who have shown interest.

3. Personalize your content: The more personal you make your emails and calls to action, the more likely your email is to be opened. Personalizing your content will help deliverability and build strong relationships with your supporters.

Now, before you send a blast, double check – is your broadcaster configured correctly?


Consent is the single most important element in setting yourself up for email deliverability success. Please take a moment to review this article on email consent.

An easy test to see if you have consent from your audience:

  1. Do your recipients have a reasonable expectation to receive email from you? This means that they requested to be put on your email list, or have opted in to be on your list.

  2. Are you sending blasts with the content and frequency requested by your recipients?

If you answered “yes” to both questions, you likely have consent from your list. If you answered “no” to either, there are multiple methods for you to achieve consent successfully.

Having consent from your supporters is the best way to influence your engagement scores, produce higher conversion rates, and build stronger relationships. Remember, an engaged email list takes more action.

📌 Important reminder: It is never a good idea to buy a list. Purchased lists are often outdated and contain bad addresses that could get you flagged as spam or blacklisted, and sending to people who never opted in to receive your emails inevitably hurts your brand and deliverability.
Regardless of the legality of this practice for your use case, emailing a purchased list violates our email acceptable use policy.

Content strategy

You have configured your broadcaster and determined the type of consent needed from your supporters. The next step is to come up with a detailed content strategy plan. 

Plan ahead

Your recipients have an expectation of how often they will hear from you and about what topics. Fulfill these expectations by creating a content strategy. Try to plan at least five blasts in the future.

For example, here is a sample content strategy for a nonprofit:

  • Email blast 1: 1st Monday - Reconfirmation email.

  • Email blast 2: 2nd Tuesday - Weekly newsletter.

  • Email blast 3: 2nd Thursday - Bi-annual appeal.

  • Email blast 4: 3rd Tuesday - Weekly newsletter.

  • Email blast 5: 3rd Thursday - Volunteer updates.

Planning ahead allows you to know what you are offering to your supporters and be in dialogue with them about what they want. Consider creating a preference management page and adding options to your nation's unsubscribe page


Testing your content goes hand-in-hand with a good strategy.

Even for your first blast, test the blast with a small group of supporters before you send to the larger pool. This allows you to gauge the reception of the email and predict future performance. For example, if you find that engagement is low for your test blast, you can easily adjust the calls to action, content, style, or subject line to spurn your recipients to action.

Large lists will require testing on a bigger scale. Learn more about NationBuilder’s A/B testing tool

A thoughtful and tested content strategy will keep your list engaged and motivated while providing you with better open, click, and donation rates.

Segment and target

Even with a carefully planned content strategy, it is crucial that you send content that is specific and targeted to small, segmented groups. If your email list is several thousand people, it is unlikely that one message is going to resonate with every individual. To get the best results from your blasts you will want segment your email list using your nation's filter tool.

You can segment via demographic information including location, age, or gender. However, the best segmentation is based on:

  1. The recipient’s previous relationship to you. For example, if someone signed up to be a volunteer, they probably want to be on the volunteer email list. 

  2. The recipient’s stated email preferences. Give your supporters content based on the frequency and subjects for which they've indicated interest.

Take another look at the content strategy from above. Here it is with the actual recipient list filled out: 

  • Email blast 1: 1st Monday - Reconfirmation email - All supporters broken into small, manageable segments.

  • Email blast 2: 2nd Tuesday - Weekly newsletter - Anyone who signed up for “newsletter” in their preferences.

  • Email blast 3: 2nd Thursday - Bi-annual appeal - All donors + Anyone who signed up for “donor list” in their preferences.

  • Email blast 4: 3rd Tuesday - Weekly newsletter - Anyone who signed up for “newsletter” in their preferences.

  • Email blast 5: 3rd Thursday - Volunteer updates - All volunteers + Anyone who signed up for “volunteer list” in their preferences.

Don’t forget to segment your audience based on the results of your testing. Message testing is how you will develop a language with your recipients, so they feel comfortable with your voice and feel like you are speaking to them personally.

For really granular email personalization you have the ability to pull information from recipients' profiles using smart fields in your email content. This allows you to reference information specific to each recipient using a single blast.

Email layout

Although your reputation is the most important aspect of email deliverability, the layout of your email can also have an effect.

Every blast will go through spam filters created by providers like Google, AOL, Comcast, Yahoo, etc. Spam filters look at the elements of an email and flag any messages that might be spam before they reach an inbox. It is not clear what email providers use to classify a message as spam, but there are some general criteria that could have an email flagged:

  • Badly written subject lines and content

  • Broken hyperlinks

  • Large images and graphics

  • A high ratio of images and links to text

  • Plain text version of the email not available

Generally, emails with fewer images and links are not as likely to be flagged as spam. 

Crafting effective subject lines

The subject line is one of the most important factors in getting your email delivered, noticed, and opened. Though more of an art than a science, there are a few established methods by which you can increase deliverability and drive the outcomes you want.

  • Length: Best practice is to keep subject lines at 50 characters and under, though around 40 is ideal.

  • Preview text should support and reinforce the subject line. Keep in mind some email providers do not display preview text.

  • Emojis & numbers 😜: Avoid starting the subject with a number or emoji, or overusing emojis, as it increases the likelihood of redirecting your email to the spam folder. However, used sparingly, emojis are a good way to stand out in a crowded inbox.

  • Spammy language: As a general rule, if it sounds like a used car commercial, it’s spammy language. Excessive punctuation or all-caps text can also trigger the spam filter.

  • Personalization: It’s beneficial to use smart fields to help get your audience's attention. First name, recent donation amount, and point person are some examples of ways to personalize a subject line.

  • Typos: Proof your subject line to make sure it’s free from errors.

  • Generate interest: There are many ways to generate interest in your audience and get them to open and take action in your email. They include asking questions and answering within the email, pointing to need or timeliness, and creating social proof (Over 9,000 of your neighbors are already signed up, e.g.). The goal is to pique curiosity, giving just enough information that they want to open the email.

Good subject line examples

Less good subject lines

[Name], your window to help giraffes is closing 🦒

🦒🦒🙅‍♂️ACT NOW!! Don’t miss this!

Thank you, [name]! See the impact of your [amount] now

Hey!! your donation is making a big splash on people across the nation. Thank you and please consider donating again!!

Can we count you in for the symposium, [name]? ✅

📣📣📣❗❗BIG event coming up!! Sign up NOW and bring a friend to the annual fundraiser in your city❗❗On time only

Will you join [point person] to help eradicate guinea worm?

50,000 raised so far in our push to eradicate guinea worm from the world at large. BIG THANKS 🙏🙇🙇

Bring relief to 9,000 flood victims with one act 🫶

YOUR donation could aid people that suffering from the devastating floods abroad. Donate Now!!

Being successful

There are a lot of steps to conquer, but the results are more than worth it. Not only will you avoid deliverability trouble with email providers, but you will build lasting relationships with your supporters.

Signs of a healthy email list include:

  • Click rates of at least 3%

  • High involvement in the email's call to action (donation, petition signature, etc.)

  • No spam reports

Signs of an unhealthy email list include:  

  • Spam reports above 0.03%

  • Bad or bounced emails at or above 3%

  • Open rates below 10%

These statistics can help as guides for the messages you send to your recipients. Remember, always ask for consent and personalize content for recipients who are engaging with your emails. Periodically remove recipients who are consistently not opening or clicking through on your emails.

A bad reputation will affect how email providers deliver email to your recipients' inboxes, but building a strong deliverability reputation will go a long way to ensuring your email outreach is effective.

Before you start building your first blast, take some time to review our article on consent. It further outlines how to build the best email deliverability standards for your nation.

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