They Sent It

Mystery offer

From Learn, the They Sent It email marketing encyclopedia · First edition · Updated October 29, 2026

A mystery offer is a promotion whose value stays hidden until the subscriber acts: a discount revealed after a click, a free gift whose contents are a surprise, or a box of unknown items sold at a set price. It leans on curiosity as well as on the size of the offer. Between February and October 2026, 864 of the 42,029 brands we follow (2.1%) put a mystery offer in at least one subject line.[4]

The three forms raise different questions. A common US framework treats a promotion as a lottery when it has three elements: a prize, chance and consideration (such as a required payment or purchase). Mystery offers that combine a purchase with outcomes of different value decided by chance, most obviously some paid mystery boxes, need the most care.[2]

Forms

  • Mystery discount. The email asks the reader to click to reveal a discount, for example on a page with a scratch card or spinning wheel, or behind a "reveal your discount" button. The amount may be the same for everyone or vary within a stated range.
  • Mystery gift. A gift whose contents are not named, which can come with a purchase or above a spending threshold ("spend $100, get a mystery gift").
  • Mystery box or bag. A box of items the buyer cannot see, sold at a set price. Examples in the archive promise more retail value than the price, and some are described as end-of-season or limited batches.

The curiosity behind it

In his 1994 review, Loewenstein proposed an information-gap account: curiosity is a feeling of deprivation that comes from noticing a gap between what one knows and what one wants to know, and it needs some starting knowledge, a gap the reader can see.[1] A mystery offer is built to open such a gap, which closes only with a click, a purchase or opening the box. The account suggests that a hint ("up to 40% off", "worth $150 or more") may help by showing the size of the gap, but that is a hypothesis for brands to test, not a finding about email.

The lottery question

A common US framework, set out by the Supreme Court in a 1954 case about broadcast give-away programs, describes a lottery as having three elements: a prize, chance and consideration.[2] State laws define these in their own ways, and that case does not settle how any state treats modern mystery offers. Some practical distinctions:

  • A mystery discount revealed without any purchase generally involves no monetary consideration. The full conditions still matter, and avoiding the lottery question does not by itself make a promotion compliant with every other rule.
  • A guaranteed mystery gift, where every buyer gets the same item and only its identity is hidden, differs from a chance to receive gifts of very different value. When a purchase is required and the gift's value is decided by chance, the purchase can supply consideration, and calling the gift free does not answer the lottery question. If it is called free, the FTC's guide on free offers also applies.[3]
  • A paid mystery box involves payment. If what each buyer receives is decided by chance, it can raise lottery and gambling questions under state law; hidden contents alone do not establish chance. Brands selling boxes whose value varies widely should get legal advice. A stated minimum retail value that every box meets helps set honest expectations but is not a legal safe harbor.

This section is general information, not legal advice.

Mystery offers in email

  • Name the form in the subject: "mystery discount", "mystery gift" and "mystery box" set different expectations.
  • Give the range or the minimum, such as "up to 40% off" or "worth at least $100".
  • Make the reveal work everywhere. A reveal that depends on a pop-up or a script that the landing page blocks on mobile loses the click it earned.
  • Set a real end date and say how many boxes there are, if stock is limited.

What brands send

Observed subject-line matches in the emails published brands sent to our subscriptions, February 1 to October 28, 2026. Days are Eastern Time.[4]

  • 864 brands sent 1,842 emails with a mystery offer in the subject, 2.1% of the 42,029 brands that sent anything.
  • Among matched subjects, mystery discounts were the most common form: 366 brands (744 emails), then mystery boxes and bags at 315 brands (681 emails) and mystery gifts at 207 brands (384 emails). A brand can appear in more than one group.
  • Wednesday was the most common day for a mystery offer email.
Brands that sent a mystery offer, by email platform
PlatformBrands sendingSent a mystery offerShare
Klaviyo34,4638412.4%
Mailchimp4,250110.3%

Platforms serve different mixes of business, which may explain much of the difference. These are observed subject-line matches, not an estimate of every offer sent: offers mentioned only in the body, or worded differently, are missed, and a few matches may be misclassified.

Examples from the archive

Common mistakes

  • Promising a range nearly nobody gets, such as "up to 50% off" when almost every reveal shows 10%, which may cost trust and response next time.
  • Selling boxes worth less than the price. A stated minimum value that every box meets may reduce complaints about value.
  • A reveal that fails, such as an expired code or a wheel that does not load, after the email has done its job.
  • Using mystery to hide a weak offer. Curiosity earns one click; the offer has to earn the order.

See also

Spin-to-win and scratch cards · Gift with purchase · Giveaways and sweepstakes · BOGO · Store credit. Entries without links are being written.

References

  1. Loewenstein, G., "The Psychology of Curiosity: A Review and Reinterpretation", Psychological Bulletin 116(1), 75-98, 1994.Back to text:12
  2. FCC v. American Broadcasting Co., 347 U.S. 284 (1954), U.S. Supreme Court (the three elements of a lottery: prize, chance and consideration).Back to text:123
  3. Federal Trade Commission, "Guide Concerning Use of the Word 'Free' and Similar Representations", 16 CFR Part 251.Back to text:1
  4. They Sent It, subject lines of emails from the 42,029 published brands that sent email in the archive, February 1 to October 28, 2026. A subject counts when "mystery" or "surprise" is followed by an offer word (gift, deal, discount, box, bag, offer, code, sale, savings, treat, reward, item), or it says "reveal your" discount, offer or code. In a hand check of 40 random matches, 40 of 40 were mystery offers.Back to text:123

First edition, October 29, 2026, by Conner Baker. Corrections are made in place and noted here. Found an error? Tell us.

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