Illustration: Allie Carl/Axios
It turns out spam filters have their own partisan divide.
Driving the news: New research shows Gmail was substantially more likely to mark Republican fundraising emails as spam during the heat of the 2020 campaign, while Yahoo and Outlook disproportionately flagged Democratic ones.
Why it matters: Email forms a huge and growing part of both parties' fundraising operations.
Any disparity in the messages making it into recipients' inboxes can have huge effects on message dissemination and fundraising during the crucial months leading up to an election.
- A new study from North Carolina State University shows that disparity can be significant, allowing candidates from one party to reach more donors than their opposition, depending on the email services those donors use.
- Email providers point to factors such as past user behavior to explain the disparity and dismiss any suggestion of platform bias.
- The research nonetheless shows potential pitfalls in political candidates' dependence on third-party technology vendors whose products frequently rely on opaque algorithms.
Context: The study focused on some key internet players.
- Gmail, Google's free product, is the nation's most popular email service.
- Yahoo, controlled by an investment management company, and Outlook, part of the Microsoft Office suite widely used in government, academia and business enterprise computing, are top competitors.
By the numbers: NC State researchers used more than 100 Gmail, Outlook and Yahoo accounts to collect more than 318,000 emails from May through November 2020.
- They came from both major presidential campaigns, as well as 78 Senate candidates and 156 House candidates of both parties.
- In general, the study found, Gmail was more than 50% more likely to mark a Republican email as spam than a Democratic one.
- Outlook and Yahoo leaned the other way: they were 20% and 14% more likely, respectively, to send Democratic emails to the spam folder.
- The trend largely held even when researchers used statistical modeling to measure emails with similar traits such as length, readability, subject line format and the use of links and images in the emails.
What they're saying: "[F]airness of spam filtering algorithm is an important problem that needs dedicated attention from email service providers," the researchers concluded.
They said that's "particularly due to the enormous influence that electronic communication has in our lives today and will have going forward."
- A Google spokesperson told Axios: "Political affiliation has absolutely no bearing on mail classifications in Gmail and we've debunked this suggestion, which has surfaced periodically from across the political spectrum, for many years."
- A Microsoft spokesperson said: "To make sure that customers do not receive unwanted or inappropriate email messages, we use anti-spam technology. Occasionally, some wanted communications may be filtered unintentionally and users can create exemptions for any filtered mail that they want to receive."
- Yahoo didn't respond to Axios' inquiries about the study.
Between the lines: Google says the study doesn't adequately account for the overriding factor for Gmail's spam filter: past user behavior.
- "Mail classifications in Gmail automatically adjust to match Gmail users' preferences and actions," the spokesperson said. "Gmail users can move messages to spam, or to any other category. Gmail automatically adjusts the classifications of particular emails according to these user actions.”
- In other words, if a campaign's emails are routinely landing in a spam folder, it's likely because Gmail recipients have previously flagged that sender's messages as spam.
The NC State researchers tried to control for that possibility by testing interactions such as opening and reading all the emails and moving them from the spam folder to the inbox.
- The latter decreased Gmail's political disparity substantially, but in both cases, the service was still more likely to flag Republican emails than Democratic ones.
- Outlook's and Yahoo's Republican lean also held even as they marked fewer emails as spam overall.
The bottom line: Even granting that these disparities are the result of user behavior rather than platform bias, they can present significant challenges for fundraising and donor outreach.