Your emails belong in the Primary inbox.

MailTail changes how Gmail reads your Klaviyo sends, so campaigns land where people actually read.

Connect KlaviyoSee how it works
CampaignsFlowsAutomationsKlaviyoGmail

Works inside your Klaviyo account. Every result measured against a holdout.

Klaviyo

now

G FUEL campaign delivered to Primary, not Promotions.

+48% campaign revenue

The shift

Most senders rewrite subject lines. The best ones fix placement.

A sharper subject line cannot rescue an email nobody sees. Placement decides whether your send sits in the pile or in the inbox.

Promotions tab

🔥 48 HOURS ONLY — 30% off sitewide
⚡️ Flash sale inside, ends at midnight
🎁 A gift for you, unlock your reward
New drop just landed, shop the collection

Stacked with forty other sale emails. Most are never opened.

Primary inbox

YYour cart is still waiting
Re: Thursday — sounds good, see you then
Payout sent — $4,182.60 is on its way

Sitting with the messages they came to the inbox to read.

How it works

One snippet, every send.

Watch a cart reminder move out of the Promotions pile and into Primary, with your template design untouched.

Nothing about your email changes.

MailTail works underneath the design, so the send your subscriber sees is exactly the one you built.

  • No redesignYour template, your creative, your copy. Nothing visible changes.
  • Two-minute setupPaste a Klaviyo API key. We handle the rest from there.
  • One-click revertEvery processed template keeps its original. Roll back any time.
9:41
Search in mail
Primary
Promotions
Social
  • E

    Everly

    9:12

    🔥 48 HOURS ONLY — 30% off sitewide

    Don't miss out, shop now

  • N

    NorthKit

    8:47

    ⚡️ Flash sale inside

    Ends at midnight

  • Y

    Your brand

    8:41

    Your cart is still waiting

    Finish checkout in one tap

  • P

    Palo Goods

    8:20

    🎁 A gift for you

    Unlock your reward

  • S

    Sunday Co.

    7:58

    New drop just landed

    Shop the collection

Before MailTailAfter MailTail

Every template, not just campaigns.

The sends that quietly earn the most are the automated ones. They get the same treatment.

  • CampaignsOne-off sends, launches, and promos
  • FlowsWelcome, browse, cart, post-purchase
  • AutomationsBack-in-stock, winback, replenishment
  • HoldoutAn untouched control on every test

Placement

Primary gets opened. Promotions gets skipped.

Why the tab matters

The tab decides the open.
The open decides the revenue.

Gmail routes roughly 68% of marketing email into Promotions, where open rates run two to three times lower than Primary. Same list, same creative, different tab, different outcome.

Primary inboxBaseline
Promotions tab2–3x lower

Relative open rate by Gmail tab. Placement depends on authentication, sender reputation and engagement, so results vary by sender.

Live the same day.

Connect Klaviyo in the morning, send optimized templates in the afternoon. No dev work, no DNS changes, no onboarding call required.

+50.8%revenue

ALP Pouches, measured against an untouched holdout on the same list.

Read the case study

Injected for you.

No snippet to paste into forty templates, no flow to rewire.

  1. 1Connect Klaviyo with an API key. No DNS changes, no dev ticket.
  2. 2We generate a variation unique to your account and inject it into your templates.
  3. 3You send as normal. Every send is measured against an untouched holdout.

Your account, your rules.

MailTail works at the template level only. We never touch your DNS, your authentication records or your sending infrastructure, and every original template is kept.

One-click revertNo DNS changesCreative untouchedFull audit log

The proof

Not a promise. A holdout.

Every account runs the optimized version against an untouched control inside your own Klaviyo sends. Open rate, click rate and revenue per recipient are compared on the same list, at the same moment.

Held equal on both sides

Same listSame send timeSame creativeSplit at random

What the difference was worth

+62.2%

Open rate

+33.8%

Click rate

+50.8%

Revenue

ALP Pouches, one of one tests won. Individual results vary by sender.

Results

Five brands. One pattern.

Gaming, apparel, maternity, pouches. Different lists, different creative, the same placement problem.

ALP Pouches

Nicotine pouches

+50.8%

Revenue lift

+62.2%

Open rate

+33.8%

Click rate

Read the case study
G FUEL

Gaming & energy drinks

+48%

Campaign revenue lift

+58%

Open rate

100M+

Emails tested

Read the case study
100 Thieves

Gaming & streetwear

+85%

Campaign revenue lift

+29%

Open rate

+118%

Click rate

Read the case study
Mina Baie

Baby & maternity

+233%

Peak revenue lift

+21%

Open rate

+138%

Click rate

Read the case study
UNRL

Athletic-leisure apparel

+109%

Peak revenue lift

+7%

Open rate

+40%

Click rate

Read the case study

Want the full
numbers?

Every study shows the holdout design, the sample, and the lift on each metric we tracked.

All case studies

Pricing

Your cheapest revenue channel.

No per-send fee and no per-seat pricing. Start free, keep the plan while the holdout keeps paying for it.

Free trial

$0

14 days or 10 templates

  • Optimize up to 10 templates
  • Full feature access
  • Analytics dashboard
  • No credit card required
Start free

Business

Popular

$299/mo

Billed monthly

  • Unlimited templates
  • Multiple Klaviyo accounts
  • A/B testing with holdouts
  • Team collaboration (up to 5)
  • Web feed for dynamic content
Connect Klaviyo

Enterprise

Custom

Volume-based pricing

  • Everything in Business
  • Unlimited team members
  • Dedicated account manager
  • Custom integrations
  • SLA guarantee
Talk to us

See it work on your list.

Connect Klaviyo, optimize ten templates free, and read the holdout before you decide anything.

Connect KlaviyoRead the results

14-day free trial. No credit card required. One-click revert on every template.