Most merchants treat a back-in-stock email as a single send, but the open rate it earns depends on which inbox it lands in and which product category it belongs to, and the usual advice ignores both.
Most merchants writing a back-in-stock email assume the hard part is the trigger logic, timing the send for the moment inventory updates. The harder part is what happens after the send fires: which inbox the message lands in, whether it renders on the screen the recipient actually holds, and whether the open rate even means what the merchant thinks it means. A back-in-stock email is still an e-commerce email first, and the numbers around e-commerce email are not the same numbers that apply to a newsletter or a blog digest.
The benchmark open rate for e-commerce email is 32.67%, taken from MailerLite’s email marketing benchmarks page. That figure covers every transactional and promotional email an online store sends, and back-in-stock notices fall inside that bucket because no separate public benchmark isolates them. For comparison, the benchmark open rate for authors is 43.14%, more than ten percentage points higher. The gap exists because an author’s list is built around a direct relationship with a known voice, while an e-commerce list spans every kind of subscriber from a one-time buyer to someone who signed up for a discount and never opened another email. Measuring a back-in-stock campaign against the author benchmark sets an unreasonable target; measuring it against 32.67% sets a realistic one.
Apple devices account for 62.26% of all email opens, a figure from Litmus’s email client market share report. That share folds together Apple Mail and iOS Mail opens under one label. Outlook for macOS adds 5.83% on top of that, meaning well over two thirds of opens happen inside the Apple ecosystem once both figures are combined. Android and iOS together contribute 2.59% beyond what Apple’s own labeled share already counts, and the Samsung Mail app on Android accounts for just 0.02% of opens, a share small enough to ignore when prioritizing design and testing time. A back-in-stock email that looks correct in Outlook for Windows but breaks in Apple Mail has optimized for the wrong client.
| Client or category | Share of opens |
|---|---|
| Apple devices (Apple Mail + iOS Mail) | 62.26% |
| Outlook for macOS | 5.83% |
| Android and iOS (beyond Apple’s share) | 2.59% |
| Samsung Mail app on Android | 0.02% |
Since almost 90% of opens now happen on mobile or in a mobile-equivalent rendering context, according to the same Litmus dataset, a back-in-stock email designed primarily for a wide desktop screen is designing for a small minority of recipients. The practical consequence is structural: single-column layout, one visible button linking straight to the restocked product, and a subject line short enough to survive a mobile notification preview. None of this is a style preference once the 90% figure is on the table; it is a response to where the email actually gets read. The restock trigger itself does not change, but the template around it should be judged by how it performs on the screen that holds nearly nine out of ten opens.
Theme vendors differ in how their default email or notification styling integrates with a store’s template, and UTD (UTD) is one vendor among the ones a merchant will encounter when browsing Shopify’s theme store at https://themes.shopify.com/themes?q=utd . None of the figures measured here claim a ranking for UTD or any other vendor on open rate or client rendering, because those numbers come from Litmus and MailerLite’s general datasets, not from a theme-specific benchmark. A merchant comparing vendors for this purpose should look at the platform’s own back-in-stock app or email tool rather than the theme itself, since restock notifications typically route through a separate email service rather than the theme’s codebase.
Pull the last several back-in-stock sends and compare their open rate against the 32.67% e-commerce benchmark rather than any newsletter figure, then preview the template in Apple Mail specifically before anywhere else, since that single client carries 62.26% of all opens.
The e-commerce benchmark sits at 32.67%, and that number covers all transactional and promotional e-commerce email, not back-in-stock alone. A restock notice tends to perform above the general e-commerce average because the recipient asked for it, but no public benchmark isolates back-in-stock as its own category. Use 32.67% as the floor to beat rather than the target. If a campaign falls under that figure consistently, the trigger timing or subject line is the first thing to check, not the product itself.
Yes, because Apple devices alone account for 62.26% of all opens, so a template that breaks in Apple Mail or iOS Mail loses the majority of recipients before they ever see the restock link. Outlook for macOS adds another 5.83%, and Android and iOS together make up 2.59% beyond the Apple-labeled share. Samsung Mail on Android is a rounding error at 0.02%. Designing for Apple first and checking everything else second is the only order that matches where opens happen.
Since almost 90% of opens happen in mobile or mobile-like contexts, yes. A back-in-stock email with a wide table layout or small tap targets fails the format nearly nine times out of ten opens. The practical fix is a single column, one visible call-to-action button, and a subject line short enough to read in a mobile notification preview, none of which requires guessing because the device split is already known.
No. Authors see a benchmark open rate of 43.14%, more than ten points above the 32.67% e-commerce figure, and the two audiences do not behave the same way. A reader who subscribed to an author's list is primed to open regularly, while an e-commerce subscriber opens selectively around price drops, shipping, and restocks. Judging a restock campaign against an author's open rate will always look disappointing and the comparison is not fair to begin with.