1. Guarantees and Device-Specific Design
When you start vetting an email marketing agency, ask them directly what guarantees they offer. Most agencies will not offer one upfront, but asking gives you leverage to negotiate lower-risk terms if your brand has solid traction. If they back their ability to drive revenue, they should be open to putting skin in the game.
Next, ask how they handle desktop versus mobile email design. Every single email sent to your list must be optimised distinctly for both screen sizes. That means building separate desktop templates at 600 pixels wide and mobile layouts at 375 pixels wide.
If an agency tells you they use a single responsive template and do not differentiate, walk away. That is a mistake.
2. Signup Form Strategy and Discount Placement
Ask what metric they optimise for when building your on-site signup forms. If their immediate answer is opt-in rate, you have a problem. Signup forms should collect zero-party data and drive immediate on-site conversion rates, not just build a bloated list of tire-kickers.
Follow this up by asking where they display the welcome discount code. A capable agency will tell you to display the code on the success step of the popup immediately. Weak agencies will tell you to hide the discount code in the first welcome flow email to protect deliverability.
Sending a high-intent shopper off your website and into a noisy inbox just to fetch a coupon destroys on-site conversion rates. You are running a store, not an inbox visit competition.
3. Tech Recommendations and Affiliate Kickbacks
Ask prospective agencies which third-party tools they recommend adding to your Shopify and Klaviyo stack, and whether they take affiliate kickbacks from those vendors. Plenty of agencies push expensive third-party apps purely to pocket recurring 20% to 30% partner commissions.
I have no issue with agencies using affiliate links if they disclose them upfront. The issue arises when an agency pitches bloated software that your store does not need simply to create a second revenue stream off your bill.
Demand total transparency on partner kickbacks before signing any contract.
4. Metrics That Matter Beyond Attributed Revenue
Ask what core performance metrics they track on a weekly basis. If their answer begins and ends with Klaviyo-attributed revenue and open rates, keep searching. Anyone can manipulate attributed revenue by widening attribution windows or blasting broad segments with high-frequency campaigns.
A proper lifecycle agency monitors the health metrics underneath the surface:
- Time to first order: The exact duration between signup and initial purchase.
- First-order AOV: How effectively your welcome series cross-sells higher-margin SKUs.
- Time between first and second purchase: The lag before a customer returns.
- Repeat product combinations: Which specific SKU pairings lead to the highest 90-day customer lifetime value.
Expect a clear performance report covering these metrics sent to you once every week.
5. Account Ownership and Retainer Deliverables
Ask who will actually manage your account day-to-day. At larger agencies, the senior strategist who sells you on the discovery call rarely touches your Klaviyo account once the retainer is signed. You end up handed off to a junior coordinator with six months of experience.
You also need a crystal-clear deliverability breakdown for your retainer. Core flow builds, including your abandoned cart, checkout abandonment, browse abandonment, and post-purchase automations, are typically built out within the first 3 to 4 months. After roughly 90 days, the initial heavy lifting is finished and the scope shifts to campaign execution, ongoing segmentation, and continuous flow optimisations.
If an agency charges an identical heavy setup fee in month six without adjusting scope or deliverables, you are overpaying.
6. Continuous Optimisation Systems
Ask what operational systems they use to guarantee account improvements month after month. The dirty secret of agency retainers is account stagnation. Once the onboarding honeymoon ends, agencies often coast on campaign scheduling and ignore the deeper automation logic.
A reputable agency runs a continuous testing schedule every 30 days. That means split-testing flow triggers, testing plain-text versus designed campaigns, cleaning unengaged subscribers, and refining segmentation to keep deliverability spotless.
If they cannot show you a documented optimisation framework, your account will eventually be put on autopilot.
Final Thoughts
Hiring an agency should free up your operational bandwidth while driving profitable retention revenue. Asking these specific questions weeds out generalist digital agencies and protects your bottom line from inflated retainers. Demand clear metrics, transparent communication, and genuine Klaviyo technical proficiency before signing anything.
If you want a second pair of eyes on your current Klaviyo setup and retention strategy, book a comprehensive account audit with the In-box team today.
