Email is the channel where an agency can produce impressive numbers quickly by doing something harmful, which makes it the channel where evidence matters most. Send more often to your most engaged buyers and revenue attributed to email rises for a quarter. Deliverability degrades, unsubscribes climb, and the list you spent years building becomes progressively less reachable, but none of that appears in a monthly report unless someone insists on it. Choosing well here is mostly about insisting on the right numbers and on a vendor who volunteers the uncomfortable ones.
Flows before campaigns, always
The durable revenue in ecommerce email comes from automated sequences triggered by behaviour: welcome, browse and cart abandonment, post purchase, replenishment for consumables, winback for lapsed buyers. They run continuously, improve with testing and do not depend on somebody having an idea on a Tuesday. Campaigns matter, but an agency whose plan is a calendar of sends is selling labour rather than infrastructure. Ask each candidate which flows they would build first for your catalogue and why that order, and listen for reasoning grounded in your purchase cycle rather than a standard list. Ask how they handle product data, because personalised recommendations and replenishment timing depend on a clean feed, and a messy catalogue quietly caps what is possible. Then ask what they would do in month one if the existing flows are already built but mediocre, since improving what exists is less impressive to present and usually worth more than adding a seventh sequence nobody reads.
Deliverability is the number that hides
Require reporting on list health from the first month: delivery rate, engagement over time by cohort, unsubscribe and complaint rates, and how much of the list has not opened anything in six months. A programme increasing revenue while complaint rates climb is borrowing against next year. Ask directly what the agency's sunset policy is, meaning at what point they stop mailing an unengaged address, and be suspicious of any answer that amounts to never, since a large unengaged segment drags delivery for everyone else. Ask how they handle authentication and what they do when a mailbox provider starts filtering. The compliance floor also belongs here: commercial email must identify itself honestly, carry a valid physical address and honour opt outs promptly, and the Federal Trade Commission's CAN-SPAM compliance guide sets out the requirements plainly. Ask whose responsibility compliance is in the contract, because agencies press send and merchants carry the liability.
Attribution, and the number that is not what it seems
Every email platform reports revenue attributed to email using an attribution window, typically counting a purchase within some days of an open or click. That number will always be larger than the revenue email genuinely caused, because a share of those buyers were returning anyway. This is not fraud, it is a measurement convention, but it becomes a problem when the agency's fee or the case for its renewal rests on it. Ask each candidate how they measure incremental contribution: whether they will run holdout groups, how they treat the overlap with paid campaigns, and what they report when platform revenue and your store's own analytics disagree. Firms that have thought about this will describe a holdout test they have actually run. It is also the point at which an email retainer should be judged next to everything else you spend, since an ecommerce marketing company managing multiple channels can shift budget to whichever is genuinely incremental only if each channel is measured honestly.
Fees, ownership and switching cost
Three fee models dominate: flat retainer, retainer plus a share of attributed email revenue, and pure performance. The revenue share models are the ones to examine, because they pay the agency more for sending more and use the inflated attribution number described above as the base. If you accept one, agree the attribution window and the definition of attributed revenue in the contract, and require a holdout test at least once a year. On ownership, confirm your business holds the email platform account and the billing relationship, that flows and templates remain in your account, and that your list can be exported at any time. Ask what the offboarding looks like in writing. Finally ask about the team: who writes, who builds, who analyses, how many accounts they carry, and whether design is subcontracted. Our index records published pricing and disclosed minimums so you can filter before any of those calls.
Questions people ask about e commerce email marketing agency
How often should we email our list?
There is no universal cadence; it depends on purchase frequency and how much genuinely useful material you have. The right method is to segment by engagement and let frequency vary, mailing engaged buyers more and unengaged addresses less. Any agency proposing a fixed number of sends per week before looking at your data is guessing.
Should the agency also handle SMS?
Often it is efficient, since the segmentation and timing overlap. Be aware the consent rules are stricter and the annoyance threshold much lower, so require separate consent capture and a conservative cadence. Ask how they would coordinate the two so a customer does not receive the same offer twice within an hour.
What if our platform is the wrong one?
Migrations are disruptive and often proposed for the agency's convenience rather than your benefit. Ask what specifically cannot be done on your current platform and what the migration costs in deliverability during the transition. Sometimes the answer genuinely is to move, but require the case in writing before month one.
How quickly should we see results?
Core flows can be live within weeks and usually show measurable revenue quickly because they capture demand that already exists. List health and campaign improvements take longer. Ask for a written expectation covering flows live by month two, first holdout test by month six, and list health metrics reported throughout.