Email automation is the use of software to send emails triggered by specific conditions — a form submission, a date, a behavioral event, a tag applied to a contact — rather than manually composing and sending to a list. Where broadcast email (a newsletter or promotional send to a full list) requires a human decision to send on each occasion, automated email flows run continuously based on rules: the welcome sequence triggers when someone subscribes, the onboarding sequence triggers when someone signs up for a trial, the re-engagement sequence triggers when someone has not opened an email in 90 days. Automation allows a single well-designed sequence to run thousands of times without proportional human effort.
The most valuable characteristic of email automation for marketing attribution is its repeatability: the same well-tested message sequence reaches every subscriber in the same cohort, which means that performance differences across cohorts are attributable to differences in the cohort (where subscribers came from, what they already know about the product) rather than differences in the sequence. This makes automated email one of the more tractable areas for measuring the downstream impact of different acquisition sources.
Common Email Automation Types
Welcome Sequences
The welcome sequence is the highest-performing automation for most email programs because it reaches subscribers at peak engagement: the moment they expressed interest. A welcome sequence of 3-5 emails delivered over 7-14 days introduces the brand, delivers the value promised in the signup offer, establishes what the subscriber can expect from the email relationship going forward, and typically includes a soft next step (read a specific post, try a specific feature, book a call). Welcome email open rates are typically 3-5x higher than broadcast sends; the content placed in those first emails is the most-read content in any email program.
Onboarding Sequences
Product onboarding sequences guide new users through the steps required to reach activation — the point where they first experience the product’s core value. An onboarding sequence triggered by a trial signup typically includes: confirmation of account creation, guidance to complete setup (import data, install a tracking snippet, connect an integration), encouragement to complete the first key action (create a first project, run a first report, invite a teammate), and escalating prompts as the trial end approaches. The effectiveness of an onboarding sequence is measured by activation rate — what percentage of new users complete the key actions that correlate with retention and paid conversion.
Re-engagement Sequences
Re-engagement sequences target subscribers who have stopped opening emails — typically defined as no opens or clicks in 60-90 days. The goal is to either reactivate these subscribers or identify them as truly disengaged and remove them from the active list. Sending to disengaged subscribers damages deliverability (ISPs interpret low engagement as a signal that the emails are unwanted) without producing value. A re-engagement sequence that starts with a simple “Still interested?” email, offers something of value to re-engage, and unsubscribes or suppresses non-responders after 2-3 attempts maintains list health and improves deliverability for the engaged portion of the list.
Behavioral Trigger Sequences
Behavioral triggers fire automations based on specific actions a contact takes: visiting a pricing page, downloading a specific piece of content, clicking a link in a previous email, completing a product milestone, or hitting a usage limit. A subscriber who visits the pricing page twice in a week is expressing intent that should trigger a more direct follow-up (a trial offer, a call-to-action to book a demo) than the standard nurture sequence delivers. Behavioral triggers allow the email program to respond to the signals contacts are giving rather than delivering the same message to everyone regardless of engagement level.
Email Automation and Attribution
Email automation creates a specific attribution challenge: automated sequences reach subscribers continuously, meaning that a subscriber who converts six months after joining the list may attribute their conversion to a welcome email, a behavioral trigger email, or a broadcast that fired the week before they converted — or to a paid ad they clicked that same week. Last-touch attribution applied to email typically credits the email that arrived closest to the conversion event, which may be a re-engagement email sent to an already-engaged subscriber who was going to convert anyway.
A more actionable attribution frame for email automation is cohort analysis: compare the conversion rate of subscribers who entered the sequence from paid search versus organic search versus referral, and track which cohorts convert at higher rates over a 30, 60, and 90-day window. This source-cohort attribution answers the more useful question — “which acquisition channels produce subscribers who respond best to our automated sequences and convert at highest rates?” — rather than trying to attribute a specific conversion to a specific email in the sequence.