US Email Politics: What share of political emails end up in spam?

Roberta PhillipsRobert Brandl

By Roberta & Robert

email politics

At the time of writing, polls pin Biden and Trump neck and neck for the US presidency. With everything still to play for, both teams are campaigning hard to appeal to a diverse electorate.

But what if your message can’t even cut through an average person's inbox? In the last 2020 presidential election, a report by North Carolina University found a significant bias in spam filtering algorithms between political parties – with each email provider marking one party’s emails as spam more than the other.

Back then, if you had a Gmail account, a right-leaning candidate’s email was 59.3% more likely to end up in spam than an email sent by a left-leaning one. If you had an Outlook or Yahoo email account, 20.4% and 14.2% more emails from left-leaning candidates ended up in spam compared to the right-leaning candidates, respectively.

Considering this, we conducted a study of our own to find out how spam filtering algorithms are impacting 2024’s Democrat and Republican email campaigns. We subscribed to all available candidates on the 2024 Candidates List (185) with email newsletters, using accounts on AOL, Gmail, Outlook, Proton, Yahoo and Zoho.

In March 2024, this comprised of 58 Democrat candidates, nine Liberal candidates and 118 Republican candidates. The inboxes of these accounts were then monitored between 1st March 2024 and 2nd April 2024. A total of 4,161 emails were collected and analyzed.

Key findings

  • Overall, Republican emails are more likely than Democrat emails to be marked as spam (16.2% vs. 12.5%).
  • Outlook was the most likely to mark Democrat emails as spam (39.6%) and AOL was the most likely to mark Republican emails as spam (32.5%).
  • The email provider with the most biased spam filtering was Proton, which was 4.7x more likely to send Democrat emails to spam (36.7% compared to 7.8%) and AOL was 3.1x more likely to mark Republican emails as spam (32.5% compared to 10.3%).
  • Outlook was the most likely email provider to send political emails of all spectrums to spam (31.7%), followed by Proton (25.9%), and AOL (15%).
  • Gmail (the most used email provider in the US) sent 6% of political emails to spam: 4.7% of Democratic emails, and 10.6% of Republican emails.
  • Zoho was the least likely to send political emails to spam (1.9%), followed by Gmail (6%), and GMX (7%).
  • A Democratic candidate sends on average 6.8 times more emails than a Republican candidate (52.7 emails per Democrat candidate, and 7.8 per Republican candidate)
  • Fewer emails are going to spam than in the run-up to the last election: Compared to the 2020 report, where more than half of emails ended up in spam, only 469 out of 4,161 emails ended up in spam (11.3%).
  • Only 5.2% of Joe Biden’s emails ended up in spam, compared to 40% of Donald Trump’s emails
  • In the study’s duration, Joe Biden sent out 46.8 times more emails than Donald Trump

How does a spam filter work, and what triggers it?

In our professional experience, we count a deliverability rate (emails that do not bounce or end up in spam) of 89% as excellent, 88 to 83% acceptable, and anything below as poor. In this study, 13.8% of political emails went to spam – giving an 86.2% deliverability rate. This, by our standards, is acceptable, but deliverability to some email providers (like Outlook and Proton) was poor. So why are so many political emails ending up in spam?

‘Spamming’ is the use of messaging platforms to send high volumes of unwanted content to a high volume of recipients. This is typically for financial gain or – more relevantly to this study – to ‘proselytize’ (convert someone to a religious or political belief).

But if users have signed up to candidate newsletters, then they surely want them – so how do they end up in spam? Different email providers have different spam filters to protect their users from unwanted content, but broadly, most of them use the following methods to flag potentially harmful content.

Spam filters can be triggered by a multitude of components, which include:

  • Not sending an initial opt-in message to confirm the recipient wants to subscribe.
  • Poor grammar and spelling.
  • Subject lines or text body in ALL CAPS.
  • Certain words (e.g. Fast cash, Meet singles, This isn’t a scam, etc.)
  • Low engagement (low percentage of people reading or responding to emails).
  • Emails without an unsubscribe button.
  • Readers blocking senders or marking email as spam can also have a cumulative effect that makes emails more likely to go to the spam folder in general.

Email providers will also use more technical methods like:

  • SPF (Sender Policy Framework)
  • DKIM (DomainKeys Identified Mail)
  • DMARC (Domain-based Message Authentication, Reporting & Conformance)

You can read more about these technical authentication processes and why they are important factors for keeping emails out of spam here.

A Democratic candidate sends on average seven times more emails than a Republican candidate

Over the course of the month, the 58 Democrat candidates sent 3,056 emails, the nine Liberal candidates sent 188 emails, and the 118 Republican candidates sent 917 emails. Although the volume of emails varied greatly between candidates, this roughly translates to 52.7 emails per Democrat candidate, 20.9 per Liberal candidate, and 7.8 per Republican candidate.

email politics newsletters

The percentage of political emails going to spam per email provider

The study used seven different mail providers: Gmail, Outlook, Yahoo, Proton, Zoho, GMX, AOL (in order of highest to lowest user base).

Constantly evolving, email providers have changed their spam filtering algorithms significantly since the 2020 findings (for example, in November 2023 Google upgraded its spam filter with “RETVec,” a newly developed text vectorizer).

In 2020, Yahoo retained about half of all the political emails (up to 55.2% marked as spam) and Outlook filtered out the vast majority of political emails (over 71.8%). Four years later, this has drastically dropped to 8.5% on Yahoo and 31.7% on Outlook (Outlook is still the most likely to filter out political emails).

Zoho Mail, like the other providers on the list, advertise a ‘multi-layered spam filtering’ system. However, only 1.9% of political emails were sent to spam, considerably below the study average of 13.6%.

percentage of political emails in spam

Republican emails are more likely than Democrat emails to go to spam (16.2% vs. 12.5%)

Overall, 12.5% of emails from Democrat candidates were sent to spam (340 out of 3,056), and 16.2% of Republican emails (128 out of 917 emails) were sent to spam. Only 0.5% of Liberal emails in the study (one email) was sent to spam, but the sample size (188) was considerably smaller.

emailtooltester email politics spam

A third (32.5%) of Republican candidate emails triggered the AOL spam filter

On average, 16.2% of emails sent by Republican candidates were sent to spam across all the email providers we tested. But this varied between 0% (GMX) and 32.5% (AOL) between different providers.

Some spam filters were also more likely to be triggered by Republican emails than Democrat emails. On the AOL accounts, one in ten (10.3%) Democrat emails ended up in spam, compared to 32.5% of Republican emails – a 22.2% difference.

Democrat Republican
Email provider % spam % spam
AOL 10.3% 32.5%
Gmail 4.7% 10.6%
GMX 9.1% 0.0%
Outlook 39.6% 24.1%
Proton 36.7% 7.8%
Yahoo 6.3% 22.3%
Zoho 0.4% 13.1%
Grand Total 12.5% 16.2%

republican emails spam

Two in five (39.6%) Democrat candidate emails triggered the Outlook spam filter

In total, 12.5% of Democrat emails went to spam – but this varied between 0.4% (Zoho) and 39.6% (Outlook). Outlook was the most likely to send Democrat emails to spam, with two in five (39.6%) of the Democratic emails triggering the spam filter.

But comparing between parties, Proton was 28.8% more likely to mark Democratic emails as spam compared to Republican emails (36.7% compared to 7.8%).

democrat emails spam

Only 5.2% of Joe Biden’s emails ended up in spam, compared to 40% of Donald Trump’s emails

Comparing the statistics for the two presidential candidates, Joe Biden sent out 46.8 times more emails than Donald Trump during the month’s research (1405 compared to 30).

In fact, one in five (21.5%) of Democrat political emails were emails from Biden, compared to one in ten Republican emails (9.4%) coming from Trump. In total, 73 of Biden’s 1,405 emails ended up in spam (5.2%) whereas 40% (12 out of 30) of Trump’s emails were marked as spam by the email providers.

One of the reasons Trump’s email count is low is because his email newsletter system is set up quite differently to the other candidates. In Trump’s case, there is no obvious email newsletter to sign up to on his campaign website, but instead an option to ‘join our movement’ or ‘volunteer’.

After signing up, the recipient also receives emails not directly from Donald Trump – but from accounts such as Donald Trump Jr or most recently through ‘Campaign Nucleus’, a SaaS platform.

EmailTooltester Email politics Biden vs Trump

What we noticed:

So why exactly are political emails ending up in spam? Using sample ‘spam’ emails from Democrat and Republican candidates, we asked our founder Robert Brandl for his insight.

Robert has more than 15 years of experience in email marketing and is an expert in email deliverability.

“Looking closely at the emails, there are a few really simple mistakes candidates are making which increase their chances of ending up in spam.

In one instance, Donald Trump’s DMARC record was failing – sending his emails straight to spam. Some candidates also used different sender names, which also increased the likelihood of appearing fishy.

donald trump email

Donald Trump's welcome email that failed domain authentication

And, though a widely encouraged practice in modern email marketing, not many candidates sent a double-opt-in message after signing up to their newsletters. This straightforward step is one of the easiest ways to legitimize bulk-email campaigns and improve deliverability rates.”


Although some providers, like Outlook, still send a significant percentage of political emails to spam. Compared to the last comparable study in 2020, less political campaign emails are being sent to spam overall – a win for the political candidates vying for the public’s support.

But despite so much money and time being poured into campaigning, it is surprising that very simple methods of practice – like sticking to a consistent sender email address – aren’t universally standard. This analysis clearly reflects how different the Democrat and Republican communication and campaign strategy is, with Biden’s team putting a vastly greater emphasis on email newsletter campaigning than Trump’s. Which strategy pays off? We will have to wait until November 5th to find out.


In this study, all candidates on the 2024 Candidates List with email newsletters were subscribed to from the following accounts: AOL, Gmail, Outlook, Proton, GMX, Yahoo and Zoho. In March 2024, this comprised 58 Democrat candidates, nine Liberal candidates and 118 Republican candidates. The inboxes of these accounts were then monitored between 03/01/2024 and 04/01/2024. A total of 4,161 emails were collected and analyzed.

The authors

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Roberta Phillips

Marketing Manager

Hey, I'm Roberta! Having worked as a digital marketer for a host of online businesses, I've tried, tested, fallen in love with and despaired with so many marketing tools. I'm excited to help you find the email marketing and CRM tools you need to thrive.

Robert Brandl

Founder and CEO

Hello! I'm Robert, an email marketing expert with over 15 years of experience. After honing my skills at an agency by serving major corporations, I founded EmailTooltester as a passion project to help small and medium-sized businesses. Connect with me on LinkedIn where I regularly share my best email marketing knowledge.

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Our Methodology

This article has been written and researched following our EmailTooltester methodology.

Our Methodology