AI inbox summaries read the first half of an email, Buzzstream finds

An editor reading pitches on their phone does not open your email first. Their inbox opens with a one-line summary written by Gmail, Apple Mail or Outlook, and that summary is now what decides whether the message is read at all. Vince Nero at Buzzstream reports that the summary almost never reads past the first half of the message.

Writing for Search Engine Journal, Nero draws on a Buzzstream study with the digital PR agency Aira of 628 AI-written summaries across the three inboxes, alongside a larger set of 39 million emails analysed by subject line and 14.3 million emails analysed by sending-domain age. The study is Buzzstream's own and the figures below are theirs.

How much the summary carries from the first half

Buzzstream measured where in a message each AI summary pulled its content from. On Gmail, 87.1 percent of the content the summary carried came from the first half. On Apple Mail the share was 82.5 percent. On Microsoft Outlook it was 65.4 percent. The second half of the message was represented in a quarter to a tenth of what the reader saw before deciding to open the email.

The summary also leans on list formatting. Microsoft Outlook used bulleted content in 92 percent of its summaries, Gmail in 65 percent and Apple Mail in 64 percent. Personalisation came through unevenly: Outlook kept a personalisation line 61 percent of the time, Gmail 11 percent, Apple Mail none of the time.

Nero adds a caveat the study records plainly: Apple Mail and Outlook misrepresented the content of the message in about one in three summaries. Gmail's rate of misstatement is not reported.

What the subject line and the opening do

Subject lines sit above the summary and the study measured them against 39 million emails. A subject stating the finding directly ("Raleigh Ranked #1") drew a 43 percent open rate and a 1.40 percent reply rate. A vague one ("New Study on Housing") drew 34.6 percent and 1.17 percent. A subject that teased the finding instead of stating it drew 39.8 percent opens against 43.1 percent for one that stated it.

The position of the key statistic inside the subject line mattered too. A number in words one to three drew a 46 percent open rate. In words four to six, 38.9 percent. Later than that, 38.1 percent. The pattern across the subject line, the summary and the opening is the same: whatever the reader is meant to notice has to be at the front.

The study separately tested sending-domain authentication across 1,588 domains. A domain running SPF, DKIM and DMARC drew a 30.1 percent average open rate. A domain running none of the three drew 7.8 percent, almost four times lower.

An outreach team that writes the finding in the opening sentence, puts the number in the first three words of the subject line and authenticates its sending domain has done the three things the study measured as moving the opens. A team that writes a two-paragraph preamble before the ask has made a message that the AI inbox summary will cut off before it starts.

Source

The New Rules Of Journalist Outreach, Based On Millions Of Emails, Vince Nero at Search Engine Journal, drawing on Buzzstream and Aira research.