--- title: "Migration ESP" id: "23326" type: "page" slug: "esp-migration" published_at: "2026-09-16T16:42:04+00:00" modified_at: "2026-10-08T12:53:59+00:00" url: "https://www.mailsoar.com/email-deliverability-issues/esp-migration/" markdown_url: "https://www.mailsoar.com/email-deliverability-issues/esp-migration.md" excerpt: "Use cases · Migration ESP How do I switch ESP without losing deliverability? ¾ of your reputation comes with you, […]" --- ###### **Use cases · Migration ESP** # How do I switch ESP without losing deliverability? ¾ of your reputation comes with you, and ¼ doesn’t. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) That asymmetry is what breaks migrations. **Your domain reputation follows you** **Your IP reputation changes** **Your sending history doesn’t move on its own** ###### **Use cases · Migration ESP** ###### **Migration ESP** ## How do I switch ESP without losing deliverability? ¾ of your reputation comes with you, and ¼ doesn’t. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) That asymmetry is what breaks migrations. **Your domain reputation follows you** **Your IP reputation changes** **Your sending history doesn’t move on its own** 01 – **What moves with you** [#trust](#trust) 02 – **What breaks migrations** [#deliverability](#deliverability) 03 – **One first impression** [#first-impression](#first-impression) 04 – **How an expert plans it** [#expert](#expert) 05 – **Email Deliverability Consulting Services** [#services](#services) 06 – **Client results and testimonials** [#client-results](#client-results) 07 – **Switching ESP FAQ** [#migration-faqs](#migration-faqs) ## Sending full volume on day one looks exactly like a spammer A migration rarely fails because of the platform. It fails because of poor scheduling and sending behavior. Placement dropped the week you switched New IPs with no history, full volume from day one. Fine at Gmail, throttled at Microsoft Providers warm up at different speeds. Bounces spiked on the first full send Your suppression list didn’t come with you. Both platforms are still sending Two sources, one domain, inconsistent signals. You migrated to fix a problem, and it followed Domain reputation moved with the domain. Weeks in, and it still hasn’t recovered No baseline was measured, so nobody can say by how much. ## Any of these will cost you deliverability and delivery quality Each signal tells providers the same thing: this sender arrived from nowhere and behaves unpredictably. Several are usually true at once, and the damage typically happens in the first two weeks. The easiest problems to prevent, and the most expensive to undo. 01 ###### Full volume on day one The fastest way to burn a new IP: providers read a sudden ramp from an unknown source as snowshoe spam. 02 ###### Warm-up compressed into a week Most senders need 4 to 8 weeks end-to-end, ramping 25–35% per send. Rushing it sets a ceiling you then spend months climbing back from. 03 ###### Suppression lists left behind Unsubscribes, hard bounces, and complainers rarely export cleanly across platforms, so they get mailed again — the fastest route to a spike in complaints. 04 ###### Authentication not migrated cleanly Every platform signs with its own DKIM keys, and an SPF record that still includes the old ESP can exceed the lookup limit. 05 ###### Dedicated IP at too low a volume Below roughly 100K sends a month, the signal is too thin, and the IP goes cold between campaigns. 06 ###### Two platforms sending at once Same audience, same domain, unaligned authentication — duplicate sends and contradictory signals. 07 ###### New tracking or link domain Tracking domains carry their own reputation — a brand-new one is unvouched for on every message. 08 ###### Migrating to escape a problem Domain reputation follows the domain. You arrive with the same damage, plus a cold-start problem. ## Recognize one of these problems? We solve them every day Our senior consultants have fixed exactly these issues for 500+ brands. Book a free 30-min call and get your action plan. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## Recognize one of these problems? We solve them every day Our senior consultants have fixed exactly these issues for 500+ brands. Book a free 30-min call and get your action plan. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## Recognize one of these problems? We solve them every day Our senior consultants have fixed exactly these issues for 500+ brands. Book a free 30-min call and get your action plan. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## You get one first impression with a new IP The plan decides whether the first two weeks build or erode your reputation — and by the time the numbers show a problem, the ramp is already compromised. A MailSoar expert sizes the warm-up to your volume and tells you what has to be in place before the first send. ## Let a MailSoar expert plan the cutover — before you send anything You don’t need to guess at a warm-up schedule, or scramble to find and fix the gaps after the first campaign. In a free 30-minute review, a consultant tells you where your placement actually stands and what has to move with you. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) Free · 30 minutes · no commitment 1 #### Baseline Real placement per provider before the move — so you have a benchmark, and know what you’re carrying over. 2 #### Plan and migrate Authentication, suppression data, and a warm-up sized to your volume — engaged segments first, both platforms controlled during the overlap. 3 #### Land at full volume Placement holds through the ramp instead of dipping — typically 4 to 8 weeks to full volume, then monitoring keeps it there. ## Let a MailSoar expert plan the cutover — before you send anything You don’t need to guess at a warm-up schedule, or scramble to find and fix the gaps after the first campaign. In a free 30-minute review, a consultant tells you where your placement actually stands and what has to move with you. 1 #### Baseline Real placement per provider before the move — so you have a benchmark, and know what you’re carrying over. 2 #### Plan and migrate Authentication, suppression data, and a warm-up sized to your volume — engaged segments first, both platforms controlled during the overlap. 3 #### Land at full volume Placement holds through the ramp instead of dipping — typically 4 to 8 weeks to full volume, then monitoring keeps it there. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## How MailSoar makes migrations easy One framework, four solutions. Most clients start with Find (baseline and plan) and Fix (execute the cutover) — then Run holds placement and Grow turns it into revenue. [AUDIT](/services-solutions/deliverability-audit/) #### Find Pinpoint exactly what’s breaking your deliverability — before spending a euro on fixes. [Discover Find](/services-solutions/deliverability-audit/) [RECOVERY](/services-solutions/infrastructure-setup/) #### Fix Roll out the technical and content fixes — DNS, warmup, infrastructure — that get your emails back in the inbox. [Discover Fix](/services-solutions/infrastructure-setup/) [PERFORMANCE](/services-solutions/recommendation-implementation/) #### Grow Turn stable inbox placement into real growth, with engagement and revenue tracked send by send. [Discover Grow](/services-solutions/recommendation-implementation/) [MONITORING](/services-solutions/ongoing-support/) #### Run Keep a senior expert watching your reputation, so issues get caught and fixed before they cost you inbox placement. [Discover Run](/services-solutions/ongoing-support/) #### Turn a clean migration into a platform for growth Talk to a MailSoar expert to uncover your deliverability issues and get a clear diagnosis of what’s causing them and how to fix them quickly. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## Brands that switched ESP without losing the inbox What MailSoar experts did to boost their deliverability, with clear results. Explore by IndustryExplore by Issue [See our case studies](/case-studies/) ‹65%→96.9% Inbox rate in 3 weeks > “MailSoar audited our email deliverability and provided recommended next steps. The audit was extremely thorough, and recommended next steps well communicated with a clear perspective on prioritization.” 60%→98% Inbox Placement > “MailSoar helped us stop the bleeding quickly, then restructure our email marketing, sales, and product approach. Problem solved!” [Read the case study](https://www.mailsoar.com/case-studies/fintech/) 35%→96% Inbox Placement > “Pierre and his team from Mailsoar have helped our company improve our email deliverability metrics to ensure that we get as many of our emails in our customers inbox as possible. Prior to his team working with us we saw a large number of emails going into spam, junk, or for the case of gmail, promotions/social. . As an online marketplace, emails are a crucial component to our supply and demand components interacting efficiently. This has helped improve that efficiency.” [Read the case study](https://www.mailsoar.com/case-studies/citizenshipper/) 30%→95% Inbox Placement > “MailSoar had a huge impact on our business and I highly recommend them. They helped us grow our open rate from ~10% to almost 50% for our eCommerce store by optimizing our email strategy and implementing various deliverability tactics. We have been using their service for a few months now, and I couldn't be happier with their knowledge, expertise, and great communication.” [Read the case study](https://www.mailsoar.com/case-studies/deliverability-at-scale/) 20%→98% Inbox Placement > “We came to MailSoar to help with our deliverability. We were so happy with their work on this, that we have continued to work with them for the past year to monitor our deliverability and to act as trusted consultants for a very important email marketing program. Our email deliverability metrics have drastically improved since starting with MailSoar. As a result of this email performance and revenue improved drastically.” [Read the case study](https://www.mailsoar.com/case-studies/ogee/) 20%→95% Inbox Placement > “We partnered with MailSoar to improve our email deliverability and sender reputation. They helped us set up a new dedicated subdomain to isolate our transactional/marketing mail flow from our primary domain, and worked with us to bring our DMARC compliance up to 97%. Since implementing MailSoar's recommendations, our email delivery rate has climbed to 99.6%. Just as importantly, the sender reputation for both humanx.co and mail.humanx.co went from "Bad" to "High". A great turnaround that's had a real impact on our ability to reliably reach our audience.” [Read the case study](https://www.mailsoar.com/case-studies/human-x/) 60%→98% Inbox Placement > “From time to time, we have had issues with our deliverability, and every time MailSoar has helped us resolve the problem and put in practices that have kept us out of trouble. We went from a place of having consistent issues with deliverability a couple of years ago to a place now where we rarely have them. And even when we do, these guys are the absolute experts in what is going on in the industry and know how to get deliverability issues resolved instantly. Cannot recommend them highly enough.” [Read the case study](https://www.mailsoar.com/case-studies/saas-b2c/) 15%→100% Inbox Placement > “Deliverability of Arcads email. We went from a very poor domain reputation to solid inbox delivery, very happy with the collaboration.” [Read the case study](https://www.mailsoar.com/case-studies/arcads/) 25%→95% Inbox Placement Rate > “We are facing email deliverability issues, and Mailsoar gave us great free advice to start, and then we went forward with an email audit from them that set us up to fix the issues we have. In just over a week, we received an audit and an action plan that we are implementing to recover our email deliverability. We are highly confident that the plan will work and be successful.” [Read the case study](https://www.mailsoar.com/case-studies/blaze-ai/) 0%→95% Inbox Placement > “I was running a complex, large-scale email campaign (...) and unfortunately, we discovered that poor hygiene and other technical issues meant almost all of our emails were going to spam. The MailSoar team was so proactive, creative, and professional. I knew I didn't just have a vendor: I had a true partner whom I could trust completely, and who cared about the success of this project as much as I did. MailSoar saved my email campaign contract. I absolutely could not have done this without them.” [Read the case study](https://www.mailsoar.com/case-studies/we-love-book-seller/) 30%→98% Inbox Placement > “Pierre understood the expectations of the job, was able to properly articulate the challenges we faced, and did a great job communicating with us through every phase of the project until it was completed. Most importantly he successfully completed the project in a timely manner. I would highly recommend Pierre.” [Read the case study](https://www.mailsoar.com/case-studies/finance/) 75%→99% Inbox Placement > “We were facing issues with email deliverability and Pierre and his team were able to help solve them.” [Read the case study](https://www.mailsoar.com/case-studies/getflex/) > “Adaptable, Excellent client service, Client-minded, Proactive, Performance, Availability, Analytical skills, Skillness, Very good relational skills, Good coaching, Helpful, Trustworthy, Punctual, Friendly, Quality of execution, Professional, Flexible, Responsive, Attentive, Good communication.” > “A growth partner that really makes a difference. MailSoar has had a major impact on our business by helping us seize new opportunities and streamline processes that were holding us back. Their expertise and support have made them a true growth partner, capable of delivering concrete results while supporting our development in a committed and sustainable manner.” > “Open rates above 40% and a rebuilt reputation MailSoar provided us with decisive expertise by quickly assessing our situation, advising us, and executing an effective plan. In a short period of time, we achieved open rates above 40% and high click-through rates, while rebuilding our reputation score. Their intervention allowed us to escape the constant pressure surrounding campaigns and calmly refocus on content.” › ## Is your situation slightly different? A migration often overlaps with these closely related problems. Start where it fits best: ## My emails land in Spam or Promotions SPAM & INBOX PLACEMENT Diagnose why mailbox providers filter you out and the levers that move you back to the inbox. [See how we fix it](/email-deliverability-issues/emails-going-to-spam/) [/email-deliverability-issues/emails-going-to-spam/](/email-deliverability-issues/emails-going-to-spam/) ## My Domain or IP got blacklisted BLACKLIST & SENDER REPUTATION Find out who listed you, get delisted the right way, and stop the block from resurfacing. [See how we fix it](/email-deliverability-issues/domain-or-ip-blacklisted/) [/email-deliverability-issues/domain-or-ip-blacklisted/](/email-deliverability-issues/domain-or-ip-blacklisted/) ## Open & click rates dropping ENGAGEMENT & OPEN RATES Find out whether it’s your content, your list, or filtering — and fix the one that’s actually failing. [See how we fix it](/email-deliverability-issues/open-click-rate-drop/) [/email-deliverability-issues/open-click-rate-drop/](/email-deliverability-issues/open-click-rate-drop/) [Explore all deliverability challenges](/email-deliverability-issues/) ## Switching ESP: FAQ My deliverability dropped after switching ESP. Can it be fixed? Yes, and the sooner the better. A slight dip in the first sends from new IPs is normal; a decline that hasn’t recovered after three or four weeks is not. It means either the ramp outpaced the trust you’d earned, or something didn’t move with you. The usual culprits are a suppression list left behind, DKIM signing on the new platform that never aligned with your domain, or volume raised faster than providers could absorb. All three are recoverable, but the fix is a controlled re-ramp on your engaged segment, not more sending. Will changing ESP fix my deliverability problem? Almost never on its own, and it often makes things worse. Domain reputation travels with your domain, so a migration carries the existing problem into the new stack while adding cold IPs on top. For most senders, deliverability issues come from sending behavior, not the platform. Find and fix the cause first, then migrate. A new platform buys you better tooling, not a clean slate. Does my sender reputation transfer to the new ESP? Most of it does. Domain reputation follows your domain everywhere, for better or worse. IP reputation doesn’t: on new IPs, you start from zero. That asymmetry is why migrations go wrong — senders assume everything resets, when the only part that resets is the one that was protecting them. How long does IP warm-up take? Plan 4 to 8 weeks end-to-end, longer if you send more than a few million emails a month. The schedule matters more than the duration: start with your most engaged recipients, raise volume by roughly 25–35% per send, and hold at each level until placement is stable. Compressing warm-up into a week is the single most common migration failure. Should I use a dedicated or a shared IP after migrating? It depends on volume, not preference. A dedicated IP only builds reputation if you send consistently enough to keep it warm. Below roughly 100,000 emails a month, the signal is too thin, and you’re better off on a well-managed shared pool. Asking for a dedicated IP at low volume is a common and expensive mistake. Should I change my domain when I change ESP? Generally, no. A fresh domain abandons whatever positive history you had and presents providers with an unknown sender suddenly sending volume — itself a spam signal. A subdomain of your existing domain is usually the right answer: it inherits organizational trust while keeping streams separate. Rule of thumb: only change domains when your website domain changes too (a rebrand, an acquisition, or a merger). ## Migrate without paying for it in the inbox Whether the move is next month or three weeks away, our consultants will measure where you stand, tell you what actually transfers, and size the ramp your volume requires. Free, no obligation. [Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) ## How MailSoar helps MailSoar helps companies change email platform without losing the inbox: authentication on the new ESP, IP and domain warming, segmentation of the first sends, then close monitoring during the ramp-up. [We Love Book Seller](/case-studies/we-love-book-seller/) migrated off an outdated ESP and went from 0% to 95% inbox placement. ## MailSoar at a glance MailSoar is an international email deliverability consultancy specializing in inbox placement, sender reputation, email authentication and email infrastructure. 25 Experts Senior deliverability consultants 500+ Clients In 20+ countries 4.9/5 Trustfolio 200+ verified customer reviews **Services**[Find](/services-solutions/deliverability-audit/) (audit) · [Fix](/services-solutions/infrastructure-setup/) (recovery) · [Grow](/services-solutions/recommendation-implementation/) (scaling) · [Run](/services-solutions/ongoing-support/) (monitoring) **Expertise**SPF, DKIM, DMARC, BIMI · IP and domain reputation · Gmail, Microsoft, Yahoo **Platforms**All major ESPs, no platform migration required **Clients**SaaS, e-commerce, finance, publishing, MarTech, high-volume senders [→ Talk to a deliverability expert](https://meetings-eu1.hubspot.com/lawrence-heslin/site) [More about MailSoar](/about/) Last updated: October 8, 2026