Win back customers: triggered emails for online stores that reach the inbox

A returning customer already knows your store, so bringing them back is easier than finding someone new. Here are five triggered emails every online store needs, the Gmail sender rules that keep them out of spam, and how to measure results honestly.

Why focus on people who have already bought?

Someone who has bought before knows your range, delivery and prices. You don't have to explain who you are again, so each repeat sale usually costs less than the first. But without reminders even a happy customer forgets the store. Triggered emails — sent automatically after a person's action — solve this without daily manual work.

Which triggered emails does a store need?

Email	When to send and what's inside
Abandoned cart	A few hours later: the cart items and a button to come back
Post-purchase	After delivery: how to use it, a request for a review
Replenishment	When the product usually runs out: a reminder with that item
Special date	Birthday or first-purchase anniversary: a personal offer
Win-back	When your usual gap between purchases has passed: what's new and a reason to return

Don't copy timings from the internet: check in your own data how many days people usually take to buy again, and tie the emails to that rhythm.

How to make sure emails get delivered

1. Set up SPF and DKIM for your sending domain. Gmail requires at least one for all senders and both for bulk senders.
2. Publish a DMARC record: it's mandatory if you send more than 5,000 emails a day to Gmail, and the From: domain must align with the SPF or DKIM domain.
3. Add one-click unsubscribe and a clearly visible unsubscribe link in the body — Gmail requires both for marketing emails.
4. Watch spam complaints in Postmaster Tools: Google recommends staying below 0.1% and never reaching 0.3% or higher.

How to measure results

• Repeat-customer share — how many orders this month came from people who had bought before.
• Cohorts in GA4: the cohort exploration in Explore shows what share of buyers return after a week, a month, a quarter.
• Email revenue — tracked through UTM tags in email links, not opens.
• Opens are unreliable: Apple Mail Privacy Protection preloads emails, inflating open counts.

Metriverra shows email revenue next to ads and organic, so you see right away how many sales returning customers brought.

In short

• A returning customer is cheaper than a new one — don't let them forget you.
• Core set: abandoned cart, post-purchase, replenishment, special date, win-back.
• Base email timings on your own purchase rhythm.
• Gmail requires SPF, DKIM, DMARC and one-click unsubscribe; keep spam complaints under 0.1%.
• Measure revenue via UTM and GA4 cohorts, not opens.

Sources: Google — Email sender guidelines · Google Postmaster Tools · GA4 — Cohort exploration · Apple — Mail Privacy Protection