The emails of a subscription business we built and run

Crenas Coliseum, a subscription to UFC fight analyses with a 7-day free trial, needs an email for every moment: the first days, a declined card, a cancellation. Here is what we built, how each part works and what we learned.

The starting point.

A 7-day free trial

New customers decide in a week whether the subscription is worth paying for.

Plans that renew

Weekly, monthly and 3-month plans renew on a card, and some cards get declined.

People who cancel

Some customers cancel during the trial or later, and some of them would come back.

Rules for email

Customers in Europe, so quiet hours, easy unsubscribe and the right to be forgotten matter.

01

Six emails during the trial, one a day, the last one the day before it ends.

Each email shows one thing worth trying, so the customer reaches the end of the week knowing what they would pay for. If they cancel, the rest of the series stops.

Move through the trial and watch the emails go out.

Example subjects. The timing is the one we use.

Day 1: the first email goes out at sign-up, or the next morning if it’s night.

    One a day, never at nightEach email waits for daytime, so it arrives when the customer can read it.
    The newest step winsIf the customer moves on, older emails that were still waiting are skipped instead of arriving late.
    Cancel, and the series stopsA customer who cancels moves to a short win-back series instead, up to 21 days after.
    02

    After a declined card, up to seven emails in two weeks, checked before each one.

    The emails go out on days 0, 1, 2, 4, 7, 10 and 14. Before each send, the system asks the payment system if the invoice is paid, and stops the moment it is.

    Choose why the card failed, then when the customer pays.

    Example subjects. The timing is the one we use.

      Checked before each sendThe payment system is asked right before every email, so nobody is chased for an invoice already paid.
      Not enough funds: one emailRetrying those cards never recovered a payment in our data, so the customer gets one clear email and the plan stops.25 declines from 7 customers over 150 days, none recovered · the business's payment records
      A fair grace periodAccess stays on for 7 days after the paid period ends, so a slow bank doesn't lock anyone out.
      03

      No emails at night, one-click unsubscribe and never the same email twice.

      Every email first reserves its place in a list, then goes out. A second attempt finds the place taken and sends nothing, and if a send fails, the place is freed for a retry.

      Try to break the rules.

      Each button is a real situation the system handles.

      Alex is on day 2 of the welcome series.

      Sending listAlex
      Welcome! Here is how to startDay 1 · reserved, then sent at 10:02sent
      Your first week, step by stepDay 2 · waiting for its turnscheduled
      Quiet hoursAn email due at night waits for the morning, so it never wakes anyone up.
      Unsubscribe in one clickEvery marketing email carries a one-click unsubscribe the email app can show as a button.
      Test without sendingEvery sequence can run in a test mode that lists who would get what, without sending a single email.
      04

      Knowing who reads, and forgetting people who ask.

      Opens, bounces and complaints are recorded for each email. After a point, people who never open stop receiving the series, and anyone can ask to be forgotten without breaking the business's numbers.

      Apply the rule, then forget a customer.

      Example customers. Blue means opened.

      Four customers, four emails each.

      Emails sent 16Opened 8Customers 4
      If tracking stops, nobody is cutWhen open data stops arriving, the rule pauses instead of dropping customers by mistake.
      Forgotten, not deleted from the totalsThe person's name and email are removed, while the counts the business relies on stay the same.
      Old data goes awayVisitor records are deleted after 90 days, and those of people who signed up but never bought, after 12 months. A scheduled clean-up does it.

      The project in numbers.

      479emails sent by the system in 30 days, none by hand

      Source: the business's email service, September–October 2026.

      What we learned.

      01Check the real state right before sending.

      Whether an invoice is paid is asked at the moment of each email, not when the series started.

      02Reserve first, then send.

      That one step is what keeps a customer from getting the same email twice, even when two jobs run at once.

      03Let the data set the rule.

      Our own records showed which declines are worth reminding and which deserve one clear email.

      04Respect protects the sender.

      Quiet hours, one-click unsubscribe and stopping for people who never open keep the sender's name in good standing.

      05Test without sending.

      A test mode that lists who would get what makes every change safe to try before it reaches a customer.

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