Operators we work with

DACH e-commerce group · 8.4M subscribers

"We came in with a German list that had been hammered through three different ESPs in five years. Gmail had us at "low" reputation, GMX was sandboxing us, and our open rate had drifted under 12%. Femke ran a 90-day recovery against the engaged 18% of the file, then ramped from there. Six months later we are back to 31% opens on the active segment, complaint rate is comfortably under 0.05%, and Postmaster Tools shows us at "high" again. The recovery framework is documented well enough that our internal team now runs the BAU work themselves."

Gmail Postmaster reputation

Low → High

+2 tiers

Open rate · active segment

11.8% → 31.2%

+19.4 pts

Complaint rate (GMail PMT)

0.31% → 0.04%

−87%

Recovery duration

— → 90 days

on schedule

French B2B SaaS · cold outbound for sales teams

"Our previous setup was three Sendgrid sub-accounts taped together with custom warmup logic in our backend. It worked until Microsoft's May 2025 enforcement landed and our 5,000+/day non-compliant senders started hitting the 550 5.7.515 wall. Blue Spirit migrated us onto a dedicated PowerMTA cluster with our own /27 in the Netherlands inside three weeks, and the cold outbound infrastructure they spec'd included the OAuth handoff with Smartlead and Lemlist. We are now sending five times the volume into Outlook with a higher inbox rate than we had on Sendgrid pre-enforcement."

Outlook inbox placement

64% → 89%

+25 pts

Daily volume capacity

14k/day → 78k/day

5.6×

Microsoft 5.7.515 rejections

2,400/day → 0/day

eliminated

Migration time

— → 21 days

as quoted

Scandinavian publisher · 1.2M paying subscribers

"A Swedish publisher with 80% of subscribers on Gmail Workspace and the long tail on local Bahnhof, Telia and Tele2 mailboxes. Our previous vendor was a US ESP that did not understand the Nordic ISP landscape at all. Saskia rebuilt our outbound on a Stockholm-fronted PMTA setup with proper IPv6 sending readiness against Bahnhof (which actually requires it cleanly) and BIMI deployment for our brand. Reader trust signals went up immediately because the brand logo started showing in Gmail and Apple Mail. Subscription churn from the email channel is down 18%."

BIMI display rate

0% → 94%

enabled

Email channel churn

4.1% → 3.4%

−18%

IPv6 acceptance · Bahnhof

— → 99.6%

enabled

Reader engagement (GMail tab)

Promotions → Inbox

tab moved

Italian D2C beauty brand · 380k DTC subscribers

"We launched on Klaviyo and outgrew it economically — at our volume the per-email pricing put us at €4,800/month for a setup that was not even using a dedicated IP. Blue Spirit migrated us onto MailWizz running on their managed infrastructure for €389/month and warmed a dedicated /29 against the Italian carrier landscape (Libero, Virgilio, plus the Outlook EU side). Inbox placement on Libero, which is where 40% of Italian consumer email lives, went from "occasional Promotions" to consistent inbox. Gross margin per send up substantially."

Monthly platform cost

€4,800 → €389

−92%

Libero inbox placement

47% → 88%

+41 pts

Cost per 1k emails

€2.40 → €0.19

−92%

Migration downtime

— → 0 hours

zero

Dutch ESP reseller · 47 enterprise tenants

"We run an ESP for mid-market Dutch and Belgian enterprises. We handle the platform layer (campaigns, templates, segmentation) and outsource the SMTP infrastructure layer because at our scale running PMTA in-house meant hiring two full-time deliverability engineers. Blue Spirit is our SMTP partner since 2022. The architecture they spec'd gives us per-tenant pool isolation so reputation problems on one tenant do not bleed into the others, and the operational discipline on DKIM rotation, BIMI publishing and DMARC migration is the kind of thing we genuinely could not afford to do in-house at our headcount."

Tenants per shared pool

unisolated → 1:1 isolated

isolated

Cross-tenant reputation incidents

4-6/year → 0/year

eliminated

Internal headcount required

2 FTE → 0 FTE

outsourced

Annual DKIM rotation events

manual → automated

47 domains

UK fintech · regulated EMI · KYC notifications

"We are a regulated electronic money institution. Our email is mostly transactional — KYC verification, transaction confirmations, security alerts. The deliverability bar is different from marketing: we cannot afford a 1% bounce on a 2FA email because that is a customer locked out of their account. Lieke set up the DMARC p=reject migration with a proper rollout plan that did not break our forwarding edge cases, deployed BIMI with our verified mark certificate, and tightened the SPF down to a clean record under the 10-lookup limit. Forwarded mail authentication (ARC) is a thing we did not even know we needed until she explained it."

DMARC policy

p=none → p=reject

enforced

SPF DNS lookups

14 (over limit) → 7

compliant

2FA email bounce rate

0.42% → 0.04%

−90%

Account lockouts (email-related)

~140/month → ~12/month

−91%

Spanish recruitment agency · IT/tech vertical

"Recruitment cold outbound is brutal in 2026. The Microsoft enforcement, the Gmail tightening, the Brevo and Mailchimp tightening of cold-mail TOS — by Q1 we were running out of providers willing to host us. Blue Spirit took us seriously, asked the right questions about our process (we have a real opt-out chain, real engagement-only segments, no purchased lists), and built us a clean cold-outbound stack with PMTA + Smartlead OAuth. They were also the first vendor to actually explain why our reputation kept tanking — turns out our previous setup was sharing a /24 with three SaaS spammers without our knowledge."

Daily reach into Outlook

1.4k → 12k

8.5×

Cold reply rate

1.1% → 4.7%

+3.6 pts

IP neighbours on /24

~80 unknown → 0 (dedicated)

isolated

Placements closed (rev impact)

14/quarter → 38/quarter

+171%

Belgian travel platform · multi-language EU

"We send across 11 EU markets in 7 languages. The receiver landscape is wildly different by country — La Poste matters in France, GMX/Web.de matters in Germany, Telenet matters in Belgium, Free.fr does its own thing. Most ESPs handle this by ignoring the per-market reality and sending everything from one US-fronted pool. Blue Spirit mapped our outbound to four jurisdiction-aware pools and tuned per-ISP throttling for the regional carriers individually. The improvement was not in the headline open rate, which already looked OK, but in the per-market booking rate from the email channel — Spain especially went up substantially because Movistar and Vodafone Spain stopped folder-routing us."

Bookings/email · ES market

0.18% → 0.41%

+128%

Movistar inbox placement

54% → 91%

+37 pts

GMX inbox placement

71% → 93%

+22 pts

Per-market reputation isolation

shared → 4 pools

segmented

EU online education platform · 240k students

"Education email has a specific failure mode that nobody talks about: the parent receives the receipt or the report card on a different domain from the student, and forwarding through corporate mail filters strips the alignment. Maria Elena ran a forwarding-flow audit that identified the ARC sealing gap, and the fix surfaced something we did not know — about 11% of our most important transactional mail was being silently demoted to spam folder at the parent's end. After the ARC sealing rollout, parent-side complaints dropped to near-zero and our customer support load on "I never got the email" tickets is down 70%."

Forwarded-mail spam classification

11.4% → 0.6%

−95%

Support tickets · "no email"

~340/month → ~100/month

−70%

ARC chain validation success

broken → 99.7%

deployed

Parent enrolment confirmations

78% → 97%

+19 pts

Danish iGaming operator · 4 EU markets

"Regulated gambling email has every characteristic that mainstream ESPs run away from: industry-flagged content, regulatory disclosures every operator has to include, cross-border sending into markets with different responsible-gambling rules. Sanne walked us through the compliance side — DSA implications for gambling promotions, GDPR data minimisation in player communications, the ePrivacy soft opt-in argument that holds up in audit. The infrastructure side was Femke's — dedicated PMTA, segregated by market, with the cooling-off blocklists synchronised against player self-exclusion. We are the rare iGaming operator with both clean deliverability and an audit trail our regulators are happy with."

Self-exclusion list compliance

manual → real-time sync

automated

Cross-market policy violations

~6/year → 0/year

eliminated

Inbox placement (iGaming-tolerant ISPs)

52% → 84%

+32 pts

Regulatory audit findings (email)

4 minor → 0

clean