10 lessons from real-world ESP migrations

Migrating to a brand new e-mail service supplier (ESP) is rarely only a easy technical change — the method additionally touches knowledge, design, deliverability, and a number of groups.

These days, increasingly more companies have been migrating to a brand new ESP. That is taking place each as a result of martech platforms are evolving with AI and since some ESPs are being sundown.

For instance, one of many first emails I ever despatched was by way of Mixpanel. (Again then, it wasn’t solely targeted on analytics and had the potential to ship e-mail.) Then there was Bronto, which Oracle acquired and ultimately sunset in 2022. One other platform, Yotpo, eliminated email and SMS functionality in 2025.

Listed here are 10 sensible classes from my expertise (and errors) throughout a number of ESP migrations. The aim is that will help you put together for e-mail migration, align with groups, keep away from slowdowns, and ultimately enhance efficiency and income by way of the migration.

What does an ESP migration actually contact?

Anybody who has ever migrated an ESP is aware of that the method goes past simply export‑import and studying new syntax for dynamic personalization. It impacts:

• Knowledge structure (lists, attributes, tags, properties, and so forth.).
• Design, templates, snippets, and blocks.
• Transactional, automated, and lifecycle flows.
• Deliverability, area, and IP status.
• A number of groups inside your group (advertising, IT, gross sales, help, authorized, ops, and so forth.).

These 10 classes are organized within the order they’re often addressed, so you may deal with them as a step‑by‑step guidelines.

Lesson 1: Align stakeholders and safe inside help

Migrating ESPs is not only a advertising venture; the migration course of impacts a number of groups and infrequently requires finances, time, and approvals that that you must plan for prematurely.

• Announce the migration internally to all related groups.
• Talk the anticipated timeline.
• Safe time and involvement from the dev, product, knowledge, and different groups.
• Get monetary approval for the overlap interval (see Lesson 2).
• Negotiate a multi‑yr contract with the brand new ESP (can embody migration‑help reductions).

Lesson 2: Plan for overlap time and staff capability

Migrating to a brand new ESP doesn’t imply you instantly cease utilizing the outdated one. 

• Count on (and finances for) a interval of overlapping prices as you pay for each the present ESP and the brand new one.
• Speak to the brand new ESP a couple of discounted migration interval whilst you’re establishing and never but sending your full e-mail quantity.
• Make sure the staff understands they’ll be engaged on two totally different platforms in parallel.
• Think about bringing in exterior assist to deal with migration work.

Deal with a migration as a chance to wash up your e-mail contact lists.

• Outline what lively or engaged means for your corporation and take away disengaged contacts.
• Suppress exhausting bounces, invalid emails, or spam traps.
• Determine what historic engagement knowledge you really want (e.g., the final 12-24 months), archiving the remainder relatively than importing it.

Sustaining disengaged contacts and outdated engagement knowledge can price you in storage charges out of your ESP. Cleansing up your lists and historic knowledge can prevent finances, and you’ll at all times export the info and retailer it externally.

Lesson 4: Take time to correctly map attributes and perceive knowledge structure

Groups typically map ESP fields rapidly and with out contemplating naming, sorts, or future workflows, solely to later uncover damaged segments and duplicated attributes.

• Map each discipline from the outdated ESP to the brand new ESP, and outline which fields truly must be migrated (and which don’t).
• Standardize naming conventions (and case sort, reminiscent of snake_case or camelCase) throughout the ESP, CRM, and analytics instruments.
• Verify knowledge sorts (boolean, string, or date) and guarantee they match the brand new system’s necessities.
• Doc how subscription preferences are saved, and confirm how the brand new ESP handles consent flags and choose‑in sources.
• Verify the sync logic to grasp how and when knowledge flows between the CRM, ESP, and different methods.

Map and save outdated attributes you didn’t migrate. As with Lesson 3, it’s really useful to again up and save all outdated knowledge and contacts externally.

Lesson 5: Deliverability and infrastructure setup are essential

Deliverability and infrastructure are sometimes handled as low‑precedence technical particulars throughout an ESP migration, however they will break your entire migration if missed.

• Accurately arrange and validate SPF, DKIM, and DMARC authentication for the brand new ESP earlier than sending at scale.
• Determine whether or not you want a devoted IP or a shared IP primarily based in your quantity.
• Plan a gradual IP or area heat‑up technique.
• Begin engagement and deliverability monitoring from day one.

They require devoted time from IT and different related groups, and these integral elements needs to be prioritized as a excessive‑precedence process.

Lesson 6: Don’t change every little thing directly

It’d seem to be the proper second to revamp workflows, rewrite copy, and improve every little thing directly. Nonetheless, each change provides danger and makes troubleshooting a lot tougher.

• Separate migration from optimization.
• Copy automations and workflows as they’re, as an alternative of rebuilding them through the transfer.
• Preserve the present copy and design for the primary part.
• Keep away from redesigning templates or rewriting message content material till after migration stabilizes.

Deal with optimization as a separate venture after the migration completes.

Lesson 7: Construct reusable e-mail advertising foundations

Use the brand new e-mail platform’s capabilities to construct a extra scalable e-mail structure. Be aware that this doesn’t contradict Lesson 6 (don’t change every little thing directly), as you gained’t be redesigning the feel and appear. 

• Create grasp templates (e.g., promotional, transactional, and automation emails).
• Construct reusable header and footer snippets that may be shared throughout all emails.
• Create modular content material blocks (hero sections, CTAs, product grids, and so forth.) to keep away from constructing campaigns from scratch.
• Centralize authorized and compliance components to make sure consistency and ease updates in every single place.

Migration is a chance to construct reusable, scalable foundations utilizing templates, snippets, and modules. Doing so will save time and cut back errors.

Lesson 8: QA your dynamic content material and personalization

Dynamic content material and personalization can quietly break, inflicting damaged variables, empty fields, or incorrect messaging for key segments. 

• Take a look at all variables utilized in topic traces, preheaders, physique content material, and code.
• Verify fallback values for each key discipline.
• Validate conditional logic (if/else circumstances, present/conceal blocks).
• Evaluate localization logic, together with language variations, foreign money, and regional formatting.

Lesson 9: Audit and join supporting platforms and triggers

As a result of automations and triggers are loosely tied to the outdated e-mail platform or exterior methods, migrating ESPs typically breaks workflows folks didn’t even know existed.

• Audit probably hidden automations in advertising, product, gross sales, and help instruments.
• Verify webhooks and API‑primarily based triggers, and reconfigure them for the brand new ESP.
• Validate product‑ and conduct‑triggered emails on the brand new platform.

Lesson 10: Plan for the 30-60 days that comply with

You want an in depth plan for the preliminary one to 2 months following a accomplished migration. This plan is the way you’ll validate the migration’s success.

• Monitor engagement, spam complaints, bounce patterns, and record churn, then periodically examine them to pre‑migration benchmarks.
• Schedule common verify‑ins with IT, product, and CRM to validate syncs and workflows.
• Preserve your migration notes and playbook up to date with what broke and the way you mounted it — simply in case that you must conduct a future ESP migration.

Begin with a transparent purpose for migrating

An ESP migration is a posh, useful resource‑heavy venture that calls for time, finances, and cross‑staff alignment. Outline your why in concrete phrases, reminiscent of price financial savings, new capabilities, improved compliance, or higher inbox efficiency. It will permit you to resolve whether or not the transfer is well worth the effort and measure success afterward.

Ask your self, “What downside am I making an attempt to resolve?”

• Is it a value determination?
• Are there new capabilities I might profit from?
• Is it a compliance or deliverability answer?
• Is it a vendor stability concern?

On the similar time, control the larger image: Inbox AI, stricter privateness guidelines, and evolving platform capabilities imply that ESP migrations will turn into extra frequent relatively than uncommon one‑off tasks.

Trying again at my very own previous migrations, those that went easily weren’t the flashiest or most superior. As a substitute, they had been deliberate effectively prematurely, concerned cross‑useful collaboration, and obtained C‑degree prioritization and robust backing from the brand new ESP’s migration staff.

Migration is a strategic initiative and never only a technical change

For those who keep in mind one factor from this text, let or not it’s this: Know your purpose for shifting e-mail service suppliers. 

Consider it like planting a winery — nothing exhibits up in a single day. For the primary couple of months, you’re juggling outdated and new platforms, simply as younger vines demand care earlier than they bear fruit. However as soon as the system matures, you begin having fun with the advantages: cleaner knowledge, higher automations, and a extra steady, scalable e-mail engine that produces outcomes for years.