MailerLite With Causality Engine: Check E-Commerce Tracking

The short answer: MailerLite and GA4 can both say "last click" about one order and name different winners, which is why MailerLite's campaign revenue rarely squares with GA4's Email row or the shop's own total. MailerLite's e-commerce tracking article records a purchase against the last campaign or automation email the subscriber clicked, inside a window you set to 7, 14 or 30 days. An ad clicked in between does not take the sale away. Compare the two on one month, keep a tenth of the list unmailed, then put the GA4 export through Causality Engine, whose first finding costs nothing at app.causalityengine.ai/start.

Disclosure: I founded Causality Engine and own it, and this page recommends it. Every claim about it links to Causality Engine's own pages.

MailerLite is an email marketing platform for small businesses and creators, with store plugins that feed orders into its reports. Causality Engine is a causal attribution product that works from a single GA4 file. They do not talk to each other: Causality Engine's home page marks Google Analytics 4 as the one source live today, and MailerLite is not on its coming-soon list. All the read sees of MailerLite is what GA4 filed under Email.

Settle these before anyone quotes campaign revenue:

1. Do the window sum. For example, a click on 1 March keeps a subscriber claimable until 31 March at 30 days (1 + 30 = 31), until the 15th at 14 and the 8th at 7. With a weekly newsletter, one click a month keeps a regular buyer on MailerLite's books all month.
2. Open the setting you already have. Account settings, Default settings, Tracking options shows the E-commerce attribution window in force, per the default settings article.
3. Fix the comparison. MailerLite's revenue, GA4's Email row and the shop's order total, identical dates.

MailerLite's count and the GA4 read, side by side

What "last click" means inside MailerLite

The rule has three parts, all in the e-commerce tracking article. The purchase goes to the last campaign or automation email the subscriber clicked before buying. The buyer must use the same email address. And any link to the connected store's domain qualifies, the homepage included, so a product link is not required. The article does not say which window is preselected; MailerLite's own reporting guide describes the method as 30-day last click.

It is a click rule, and that deserves credit: the tracking options article explains how Apple Mail Privacy Protection registers opens nobody made, and clicks are untouched by that. The orders API reference adds the edges: attribution is worked out when an order is marked complete, and never for a pending order or a buyer with no subscriber record.

The switches are per campaign (Track links on the Campaign details step), per automation and global, and the tracking options article says all email tracking is enabled by default.

What the rule never consults is anything outside MailerLite: "last" means last among its own emails.

A worked example: one month, three windows

For example, take one month. These numbers are an illustration, not anyone's report.

• The shop's order total: 1,180 orders at €48 each, 1,180 x 48 = €56,640.
• MailerLite, 30-day window: 402 orders, 402 x 48 = €19,296.
• GA4's Email row under Paid and organic last click, which Google's attribution help says sends all credit to the last non-direct channel: 213 orders, 213 x 48 = €10,224.
• Google Ads claims 455 conversions and Meta 397 purchases.

Three claims: 402 + 455 + 397 = 1,254 against 1,180 booked, so 1,254 - 1,180 = 74 orders are claimed more than once. The email gap alone is 402 - 213 = 189 orders, 189 x 48 = €9,072: buyers who clicked an email inside 30 days and arrived for the purchase by another route.

Now change only the dropdown. Say the same month reads 331 orders at 14 days and 268 at 7. Then 402 - 268 = 134 orders, and 134 ÷ 402 = 33% of the claim rests on a setting.

No Causality Engine figure is made up here. Per how it works, a read returns for Email, as for every channel in the file, the share the model says the channel caused beside a last-click share rebuilt from the same export, a data-health score out of 100, and a verdict of raise, cut or hold with a one-region test attached. If its Email share sits nearer GA4's than MailerLite's, the next move is a test, not a cut.

UTM tags: the switch that puts MailerLite in GA4

MailerLite's Google Analytics article says enabling the option adds a UTM tag to a campaign's links. For a campaign it is the UTM tags toggle under Tracking options; for an automation email, a checkbox in the sidebar of the email step. Custom values go in the UTM code fields on the Link tracking tab of Account settings.

The article prints no default values, so read those fields yourself. What GA4 needs is narrow: Google's channel definitions file a session under Email only when its source or medium is email, e-mail, e_mail or e mail, and call anything that matches no rule Unassigned. A source of mailerlite with a medium of newsletter fails that test. Untagged links fare worse, since Google's note on direct traffic says source information is lost when links lack UTM parameters.

The free check: a holdout built by hand

MailerLite documents an A/B split campaign, in which every recipient still gets a version. Its help pages cited here describe no way to mail a random share and withhold from the rest, so this part is by hand, from documented pieces. Export the list, mark a random tenth in a spreadsheet, and import those rows into a group called Holdout. Then, on the campaign's Details page, open Select recipients and click Exclude group; the exclusion article says excluded subscribers are ignored even when they sit in a list you included.

For example, 15,000 subscribers become 1,500 held out and 13,500 mailed, nine for every one. After a month the shop's orders show 648 from mailed addresses and 61 from the holdout. Without email the mailed group would have placed about 61 x 9 = 549, so the month's campaigns caused 648 - 549 = 99 orders. That figure is enough on its own.

Then the channel view, and where it stops

MailerLite bills by subscriber count, per its pricing page, and its tracking arrives switched on with a window that stretches to 30 days. The longer the window, the more of a subscriber's ordinary shopping is filed as email revenue, and the easier the next subscriber tier is to defend.

The holdout measures your campaigns, not how email ranks beside paid search or social. For that, drop the GA4 file on the start page: the preview is worked out in your browser and names the channels hiding inside Direct. Causality Engine, which I founded, sells the full read at €99, paid once and refundable for 30 days (pricing, checked on 11 November 2026).

Know its limits first. The start page asks for your purchase key event and 12 months or more. The how-it-works page calls a channel under 1% of credit on both methods too small to act on. And the read gives Email one line: which automation step earned its keep stays a MailerLite question.

See also

• MailerLite: plans, limits and who it fits
• How to use MailerLite: selling a paid newsletter through Stripe
• MailerLite's affiliate program terms
• Causality Engine: what a read is and costs
• How to use Causality Engine: from export to a budget decision
• Causality Engine's affiliate program terms
• How to find what Direct traffic is hiding: where untagged email clicks end up

FAQ

Is there a MailerLite connection or app for Causality Engine?

No. Nothing is installed in MailerLite and no API key changes hands. Causality Engine works from the Attribution paths file you download from GA4.

Which attribution window does MailerLite start with?

The help article lists 7, 14 and 30 days without naming a default, and MailerLite's reporting guide speaks of 30-day last click. Check Tracking options in your own account.

Does MailerLite count a sale after an open with no click?

Its rule and its orders API both refer to the email the buyer clicked, so the click is what places the order in a report.