Your last campaign was probably read by an AI before it was read by a human. Apple Mail and Gmail now summarise messages into a single line; shoppers ask assistants what to buy and get a paragraph back. The words your team agonised over are being rewritten, compressed and re-voiced by a model you don't control — and for most brands, what comes out the other side is generic.
What actually happens when an AI inbox compresses your email?
An AI summary keeps facts and drops texture. Give a model 150 words of carefully voiced copy and it will reliably preserve what's on offer and when it ends — and just as reliably discard the rhythm, the wit and the phrasing that made the message yours.
That has two consequences. First, if your offer isn't stated plainly, it can vanish entirely: a teaser subject line like "Something special is waiting…" summarises to nothing at all. Second, every brand that writes vaguely ends up sounding identical after the squeeze — the model replaces your voice with its own house style.
The one line an AI shows before anyone opens is now the most valuable real estate in the message. Most brands don't even know what theirs says.
Why does this matter beyond the inbox?
The same dynamic plays out in AI search. When a shopper asks an assistant for "the best laptop deal this weekend", the answer names one or two brands and describes them in a sentence. Whether your brand gets named — and whether the description sounds like you or like a category average — depends on the language you've published everywhere, not just in one email.
This is measurable. You can score how often assistants mention a brand, how favourably they describe it, and which published phrases earn the citation. We call this AI visibility, and it behaves like SEO did in 2005: most brands ignore it, a few compound an advantage.
How do you write language that survives?
Three structural habits make more difference than any amount of polish:
- Lead with the offer, in numbers. "Up to 40% off for 24 hours" survives any summariser. "Don't miss our biggest event of the season" survives none of them.
- Make the brand the subject of the sentence. Models echo grammatical structure — copy that says "Sephora has free next-day delivery on orders over £25" gets the brand named in the answer; copy that buries the brand in a footer doesn't.
- Test the compressed version, not just the original. Before sending, summarise your own message with the models your customers' inboxes run. Treat the one-line output as a first-class deliverable — write, test and optimise it the way you would a subject line.
None of this means flattening your voice into bullet points. It means knowing which parts of a message carry the brand and which parts carry the facts, and making sure both survive independently. That's a writing discipline — and it's exactly the kind of constraint that's better enforced by a system than a style guide PDF nobody opens.
Where to start this week
Pull your last ten campaigns, run each through a current model with the prompt "summarise this email in one line", and put the outputs in a spreadsheet next to your subject lines. You'll know within an hour whether your offers are surviving and whether anything in the summaries still sounds like you. If the answer is no — that's the brief.
Frequently asked questions
What is AI summarisation in email marketing?
Apple Mail, Gmail and other clients now use AI to compress each email into a one-line summary shown before anyone opens it. That machine-written line — not your subject line — is often the first thing a customer reads.
How do I check if my brand voice survives AI summarisation?
Run your recent emails through the same AI models your customers' inboxes use and compare the summaries against your copy. If the offer, the urgency or the tone is missing from the one-line version, your voice isn't surviving. Jacquard's Brand Insights tracks this automatically.
How do I write email copy that AI summarises well?
Put the offer and the brand name in the first sentence, keep one idea per message, use concrete numbers rather than vague claims, and avoid wordplay that only works at full length. Then test the summarised version the way you'd test a subject line.
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