Triggered email flow
A triggered email flow is an automated sequence that sends when a subscriber performs an action or meets a condition. Flows run continuously and can fail silently for days before the breakage surfaces.
Definition
What a triggered email flow is
A triggered email flow is a sequence of emails that starts automatically when a subscriber performs a specific action or meets a defined condition. The trigger might be a form submission, a purchase, a cart abandonment, or a change in subscriber status. Once triggered, the flow sends a series of messages according to timing rules and logic steps defined in the journey.
Each subscriber enters the flow individually. The flow does not send to everyone at once. It processes new entrants as they arrive, and each subscriber moves through the sequence at their own pace. A welcome flow might send the first email immediately, the second email two days later, and the third email five days after that. The timing is relative to the subscriber's entry point, not a fixed calendar date.
Common trigger types
What starts a flow
Subscriber action
The subscriber performs an action in the product or on the website. They create an account, make a purchase, abandon a cart, or click a link in a previous email.
Data change
A field in the subscriber's profile updates. Their subscription tier changes, their billing status moves from active to overdue, or their engagement score drops below a threshold.
Time-based condition
The subscriber reaches a date or duration milestone. Thirty days since their last purchase passes, their trial period ends, or their renewal date arrives.
Inactivity threshold
The subscriber stops engaging. They have not opened an email in 60 days, have not logged in for 90 days, or have not made a purchase in six months.
How flows differ from campaigns
Flows run continuously, campaigns run once
A campaign is a one-time batch send. You select a list, schedule a time, and the platform delivers the message to everyone on that list within a defined window. Once the batch completes, the campaign is finished.
A flow remains active indefinitely. New subscribers continue entering as long as the flow is live. The platform processes each entrant individually, applying the same sequence logic to every new subscriber who meets the trigger condition. This continuous operation is what makes flows powerful for lifecycle marketing, but it is also what makes breakages hard to detect.
Why flows fail silently
The platform logs success even when nothing arrives
I worked with a broadcaster whose Saturday newsletter flow stopped sending for the first hour of the window. The platform reported every send as successful. The inbox stayed empty. Subscribers were entering the flow, the platform was processing them, but the final send step was failing without triggering an error. The flow ran in this broken state for an hour before a manual check caught it.
Late arrival in the first 20 or 30 minutes is almost always a scheduling issue, not a genuine breakage. The platform queued the send but did not process it on time, usually because of timezone drift or send-time optimisation logic that pushed the message outside the intended window. By the time the first subscriber complained, the backlog had cleared and everything looked normal in the logs.
The platform does not distinguish between a send that arrived late and a send that never happened. Both show as success in the metrics dashboard. The only way to know the inbox stayed empty is to check the inbox directly, which is what Telltide monitors do continuously.
Common failure modes
How triggered flows break
Delay step stops firing
A wait step in the sequence fails to advance subscribers to the next step. Subscribers sit in the delay indefinitely, and the rest of the flow never runs.
Merge tag references missing field
The content includes a dynamic field that has been renamed or removed. The platform replaces the tag with an empty string, and the email sends with a blank space where the personalised content should be.
Split logic routes everyone to the same branch
An audience split checks a condition that always evaluates false. Every subscriber routes to the fallback path, and the other branches never fire.
Suppression rule blocks the entire flow
An email suppression rule prevents sends to a segment that overlaps with the flow's entry criteria. Subscribers enter the flow but are immediately suppressed at the first send step.
How monitoring catches flow failures
End-to-end checks from trigger to inbox
Telltide enrols test identities into live flows and waits for each expected email to arrive. The test identity performs the trigger action, enters the flow, and should receive the sequence on the defined schedule. If an email does not arrive within the expected window, the monitor alerts.
The check runs from the inbox. Telltide does not parse platform logs or validate flow configuration in the ESP's interface. It triggers the flow, waits for the send, and checks whether the inbox received it. This catches delay-step failures, broken merge tags, and suppression-rule conflicts that platform-side checks miss.
For flows that should send on a recurring schedule, heartbeat mode checks that the expected send happened in the expected window. If the flow skips a cycle, the absence triggers an alert. This is how we catch the symptom when a flow silently stops firing, not an error event in the platform.
Related terms
Concepts that travel with triggered flows
- Campaign vs flow: the distinction between one-time sends and continuous sequences.
- Audience split: a decision step in a flow that routes subscribers based on conditions.
- Dynamic content: personalised content blocks that change based on subscriber data.
- Email suppression: rules that block sends to specific subscribers or segments.
Monitor triggered flows from the inbox
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