Good morning, Chase and Jimmy here.

Most ESP migrations go sideways for the same three reasons... and all of them are avoidable.

We've watched brands torch months of deliverability progress by rushing their warmup, trusting open rates for segmentation (thanks for nothing, Apple MPP), or trying to flip the switch on everything at once.

This week, we're breaking down the exact migration playbook that keeps your sender reputation intact: which subdomain setup protects your root domain, the warmup sequence built around buyers instead of openers, and the metrics that actually tell you if something's going wrong before it becomes a disaster.

Also inside:
✔️ Inside the send: How Jolie turns a filter reminder into a brand moment
✔️ Knowledge drop: Turn returns into revenue
✔️ DTC wins: Behave Candy lands in Target

Let’s get into it.

Inside the send: How Jolie turns a filter reminder into a brand moment

Inboox's AI Breakdown pulled apart this retention email from Jolie and found a masterclass in simplicity. The header hits with "CLEAN WATER, DAILY," the body keeps it tight with one short paragraph and a clean product visual, and the CTA is direct enough that you don't have to think.

What worked:

• Visuals complement the message instead of competing with it

• Clear, single-action CTA that removes friction

• Concise, user-focused copy that earns every sentence

Where it could push further:

• A limited-time offer would add urgency to a passive reminder

• A quick customer quote would reinforce why the product matters

• More contrasting colors on the CTA to make it pop harder

That's the power of Inboox. Access 1.5M+ real Shopify emails, get instant AI breakdowns on what works (and what doesn't), plus send-time data, full HTML, and more.

→ Start your free trial

The ESP Migration Strategy That Protects Your Deliverability

Switching email service providers sounds straightforward until you realize one wrong move can tank your deliverability for months.

Most ESP migrations fail because brands rush the warmup, send to the wrong segments, or try to move everything at once. The result? Emails landing in spam, engagement dropping, and revenue taking a hit while you scramble to fix it.

Here's how to migrate without destroying your sender reputation in the process.

Why most ESP migrations go wrong

There are three main ways brands screw up migrations:

Rushing the warmup. Going from zero to 100,000 emails overnight on a new domain is a guaranteed way to get flagged as a spammer. Inbox providers see sudden volume spikes as suspicious, and they'll throttle or block your emails until you prove you're legitimate.

Sending to the wrong segments. Starting with "90-day openers" seems logical until you realize that open rates are inflated and unreliable thanks to Apple's Mail Privacy Protection. Those "engaged" subscribers might not be engaged at all.

Moving everything at once. Trying to migrate your entire email program, all your automations, and your full list in one shot is a recipe for chaos. Too many variables, too many things that can break, and no way to isolate what went wrong when deliverability tanks.

The right approach is slower, more methodical, and focused on protecting your sender reputation above everything else.

Step 1: Start with a fresh subdomain (and protect your root domain)

Never warm up using your root domain. Always use a subdomain.

Here's why: if your warmup goes sideways, you can abandon the subdomain without damaging your root domain's reputation. But if you warm up on your root domain and things go badly, you've just torched your primary sending domain and there's no easy way to recover.

Set up a subdomain like mail.yourbrand.com or email.yourbrand.com. Inbox providers treat this as a completely new sending domain with zero history. That means you're starting from scratch, which is exactly the point. You need to build trust slowly and deliberately.

Make sure your DNS records are set up correctly (SPF, DKIM, DMARC) before you send a single email. Misconfigurations here will kill your deliverability before you even start.

Step 2: Configure your new ESP platform before sending anything

Before you warm up, your new ESP needs to be configured exactly right. This isn't the time to experiment with new settings or try out features you weren't using before.

Here's what to lock down:

Attribution and suppression settings. Make sure your suppression lists (unsubscribes, bounces, complaints) are imported and active. The last thing you need is sending to people who already unsubscribed.

Time zone settings. If your old ESP was sending at 10am EST and your new one defaults to PST, your sends will be off by three hours. Match your old timing exactly.

Integrations and automations. Set everything up, but don't activate it yet. You need a controlled environment during warmup. Every email sent should be part of your planned rollout, not an automation that fires unexpectedly.

Forms and signup flows. Import these but keep them paused until warmup is complete. You don't want new signups getting added to a warmup-in-progress.

The goal is to replicate your old setup as closely as possible while keeping everything in a controlled state. You'll turn things on gradually as warmup progresses.

Step 3: Connect your ecommerce platform and import historical data

Integrate your ecommerce platform before you start warming up. You'll need this data to build smart segments and effective automations.

Import:

• Purchase history. Who bought what, when, and how much they spent. This is critical for segmentation.

• Customer profiles. Names, locations, signup dates, and any custom attributes you've been tracking.

• Behavioral data. Browsing history, cart activity, product views. The more data you have, the better you can segment.

Once the data is imported, use this as an opportunity to refresh your automations. Don't just copy-paste your old flows. Review them, update the copy, tighten the timing, and remove anything that wasn't performing.

Migrations are a forcing function to clean up your email program. Take advantage of it.

Step 4: Build a segmentation strategy around buyers, not openers

This is where most migrations go wrong. Brands start by sending to their "most engaged" segment based on opens, which is a terrible idea.

Open rates are unreliable. Apple Mail Privacy Protection inflates them. Gmail's image caching skews them. You can't trust opens as a measure of engagement anymore.

Start with your most reliable segment: recent buyers.

Here's the warmup sequence that works:

Week 1: Recent buyers (30 days). These are your most engaged customers. They just bought from you. They're expecting to hear from you. Start here.

Week 2: Recent clickers (30 days). People who clicked in the last month are actively engaged even if they didn't buy. Add them next.

Week 3: Buyers (60 days). Expand to people who bought in the last 60 days.

Week 4: Buyers (90 days) + engaged clickers (60 days). Keep expanding based on purchase and click behavior, not opens.

Use a 40% growth model. If you sent to 10,000 people in week one, send to 14,000 in week two (10,000 from week one + 4,000 new). This gradual ramp shows inbox providers you're legitimate.

Always include your previous batches in each new send. Consistency matters. Inbox providers are watching for steady, predictable sending patterns.

Step 5: Monitor your reputation metrics obsessively

During warmup, you need to watch your metrics like a hawk.

Here's what actually matters:

Click-through rates. This is your most reliable engagement metric. If CTR drops, you've got a problem.

Complaint rates. If people are marking your emails as spam, inbox providers will notice. Keep this under 0.1%.

Bounce rates. Hard bounces should be near zero. Soft bounces should resolve quickly. If bounces are spiking, something's wrong with your list or your setup.

Inbox placement by domain. Check how you're performing at Gmail, Yahoo, Outlook, and other major providers separately. Sometimes one provider will throttle you while others don't. You need to know where the issue is.

Open rates can give you directional insight, but don't obsess over them. They're not reliable enough to base decisions on.

If you see performance drop, stop immediately. Don't keep sending and hope it improves. Identify the problem (bad segment, technical issue, deliverability hit), fix it, and restart from your last successful send volume.

What to do when things go wrong (because they might)

Even with a perfect plan, warmups can hit snags. Here's how to recover:

Performance drops suddenly. Pull back to your last successful send volume. If you were at 20,000 and performance tanked, drop back to 10,000 and rebuild slowly.

One provider is blocking you. If Gmail is fine but Yahoo is bouncing everything, you've got a provider-specific issue. Segment by domain and warm them up separately at different paces.

Engagement is lower than expected. Check your list quality. You might have bad data. Tighten your segmentation and focus on more recent, more engaged subscribers.

Automation fired during warmup. If an automation accidentally sent to people outside your warmup plan, assess the damage. If it was a small number, you're probably fine. If it was significant, you may need to pause and recalibrate.

The key is catching issues early and adjusting before they become disasters. Don't power through problems hoping they'll resolve on their own.

When to turn on automations and full sends

Don't rush this. Warmup isn't over just because you've hit your full list size.

Here's when it's safe to flip things on:

You've completed 4-6 weeks of controlled sending. This gives inbox providers enough data to trust your sending patterns.

Your engagement metrics are stable or improving. CTR is solid, complaints are low, bounces are minimal.

You've sent to your full active list at least twice without issues. Consistency matters. One good send isn't enough.

Once you hit these milestones, start turning on automations one at a time. Don't activate everything at once. Turn on your welcome series, monitor it for a few days, then turn on abandoned cart, then browse abandonment, and so on.

Same with campaigns. Start with your regular send cadence and make sure everything's stable before you ramp up frequency or try new things.

What a successful migration actually looks like

A good ESP migration takes 6-8 weeks minimum. Anything faster is probably cutting corners.

Here's what success looks like:

• Deliverability metrics match or exceed your old ESP

• Engagement rates are stable or improving

• No major spam or deliverability issues during warmup

• Automations are running smoothly on the new platform

• Your team is comfortable with the new system

If you hit all of those, you've done it right.

Here's what to focus on:

• Start with a fresh subdomain to protect your root domain

• Configure your platform completely before sending anything

• Import all historical data and use it to build smart segments

• Warm up with buyers and clickers, not openers

• Monitor metrics obsessively and adjust immediately if things go wrong

• Turn on automations gradually after warmup is complete

ESP migrations are high-risk, high-reward. Done right, you get better features, better support, and better economics. Done wrong, you tank your deliverability and spend months recovering.

Take your time, follow the process, and prioritize your sender reputation over speed. Your revenue depends on it.

Knowledge drop:

Jimmy shares a simple AI prompt that extracts the top reasons customers return your products, using their exact words. Plug it into your support emails and you'll find the objections killing your conversions before they happen.

DTC wins:

The low-sugar, clean-label gummy brand, Behave, just hit Target shelves. Behave combines chef-driven flavor with food science to make candy that doesn't spike your blood sugar. Going from DTC to a major national retailer is a big move, and Target's the right stage for a better-for-you brand with mainstream appeal.

Annnnd that’s a wrap for this edition! 

Thanks for hanging with Chase and me, always a pleasure to have you here.

If you found this newsletter helpful (or even just a little fun), don’t keep it to yourself! Share ecomemailmarketer.com with your favorite DTC marketer. Let’s get them on board so they don’t miss next week’s drops.

Remember: Do shit you love.

🤘 Jimmy Kim & Chase Dimond

PS - Your next best customer might be reading this right now. Want in? Email Jimmy to sponsor this newsletter and more.

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