An email marketing case study template that survives scrutiny

Most retention case studies read like a highlight reel: a big percentage, a client logo, a paragraph of praise. They're built to be skimmed once and forgotten — which is fine, until a prospect actually reads one closely and notices there's no period, no metric definition, and no source for the number doing all the work.

Why most retention case studies don't convert

The pattern is consistent: a headline stat with no baseline ("+340% revenue from flows"), no stated time window, and no mention of which tool produced the figure or what it's measuring. A skeptical reader — and the prospects worth winning are skeptical — can't verify any of it, so it reads as marketing rather than evidence. The fix isn't a better percentage. It's structure that makes the number checkable.

The template

Eight blocks, each answering one question a prospect will otherwise ask themselves:

• Client context — sector, rough size, anonymous or named.
• The situation — what wasn't working, in one or two sentences.
• What we changed — the specific action, not a vague "optimized the flow".
• The flow and the period measured — name it, date it.
• The metric and its definition — attributed conversion value, revenue per recipient, whatever it is, named precisely.
• The result, as attributed by Klaviyo — the number, sourced.
• What it does not prove — one honest sentence. This is the block most agencies skip, and the one that makes the rest credible.
• What we would do next — shows ongoing judgment, not a one-off lucky result.

A worked example

Same underlying result, written two ways (figures below are illustrative, not a real client's):

Written wrong: "We boosted this client's email revenue by 210%! Our welcome flow rewrite was a game-changer for their business."

Written to the template: "Ecommerce apparel brand, mid-size. Their welcome flow hadn't been touched in over a year and converted below the account's other flows. We rewrote the subject lines and cut the sequence from 6 emails to 4. Over the following 90 days, Klaviyo attributed $18,400 in conversion value to the flow, versus $8,600 in the prior 90-day period — a per-recipient value of $3.10, up from $1.60. This doesn't establish that the rewrite alone caused the increase; seasonality and list growth both changed in that window too. Next, we're testing a further split on the second email's send delay."

The second version is longer and makes a smaller claim — and it's the one a prospect can actually trust, because every sentence in it can be checked against something real.

The four credibility markers

Whatever format you use, four things separate a case study that holds up from one that doesn't: an explicit time period, a named and defined metric, a stated data source, and the absence of a causal claim. Miss any one of the four and a careful reader notices — usually the same reader who was closest to signing.

Anonymous vs named

You don't need the client's name for any of this to work. An anonymous case study with a real period, a real metric and a real source is more credible than a named one missing all three. See what you can publish about a client without asking first for where the line actually sits.

Turning it into something you can send

A PDF case study gets attached to an email, opened once, and forgotten in a downloads folder. A dated, hosted page with the same content gets forwarded, reopened, and — because it's a live URL rather than a static file — can be checked at any point rather than trusted on faith the day it was sent. Whatever you publish, keep the underlying figures frozen at the moment you send it, so the link a prospect opens next week shows the same thing it showed when you sent it.