emailrules.today
Stop 2 of 8Week oneThe hour before send

ESP

Email service provider — the tool that sends your campaigns (e.g. Klaviyo, Mailchimp, Braze).

Say it out loud

“The tool we send from. Klaviyo, in our case. It is not the same thing as our website or our inbox.”

An ESP (email service provider) is the platform where contacts live, campaigns are built, and sends are executed. It is not your website host, not your DNS provider, and not the mailbox your recipients read in. Confusing those four is the most expensive vocabulary error in this job.

The testFour different companies, and the question each one answersOur framingscrolls →
"Why didn't this send?" → your ESP

Klaviyo, Mailchimp, Braze, HubSpot, Salesforce Marketing Cloud.

"Why doesn't it trust us?" → your DNS host

Cloudflare, GoDaddy, Route 53. Where the proof of identity is published.

"Why is it in spam?" → the mailbox provider

Gmail, Outlook, Apple Mail. They decide, and they do not tell you why.

"Why did nobody buy?" → you

No platform has ever fixed this one.

An afternoon spent in the wrong one of these four is the most common wasted afternoon in email marketing.

Nobody's

Nothing to action — it changes a number or a risk you report.

What goes wrong

Escalating a spam-folder problem to ESP support. They can see that they handed the message over successfully, which is nearly always true and nearly never the answer.

See also

Where this sits

Stop 2, you build the message. You choose a From address, write a subject line, and add the things the law requires to be in the message.

← BeforeGPCNext →From domain

FAQ

Awkward questions

Who is this actually for?

People who ship email and are too busy to re-read every PDF: week-one marketers, lifecycle/CRM, deliverability, multi-country ops, DTC brands, agencies — on Klaviyo, Mailchimp, Braze, HubSpot, SFMC, or something else. Pick your tool and geos so product-specific pages only appear when they match. EU and UK are first-class filters. Not for people who sell tools about email and need a fake score to demo.

Why only ~40 rules? Isn’t that… thin?

On purpose. A wall of 400 undated “best practices” is how you look busy and still get burned. Every page needs a primary source we actually read. Thin and checkable beats fat and folklore. Europe, bulk inbox rules, measurement honesty, and protocol topics like BIMI/DMARC policy are on the shelf when we can cite them — not every Member State and not every vendor myth. Coverage map lists what we still refuse to invent.

Is this legal advice?

No. If it were, you’d have a billable hour and a longer PDF. This is a dated operator reference written by an email geek. Confirm anything high-stakes with counsel who knows your facts. Same for “will this make me compliant?” — no tool does that. Lawyers and judges do. We say what the sources say and what to do first on Monday.

Why no trust score out of 100?

Because we refuse to invent a number you can’t audit. Fake scores sell seed tests and panic. You get findings, dates, and links. If that feels less exciting than a red dial, good — you’re not the red-dial customer.

Why should I trust you more than my ESP’s blog?

ESPs sell seats. Seed-score vendors sell fear. AI invents citations when nobody watches. We sell nothing today — no pixels, no placement scores, no affiliate — so we can say when a tool is the problem. A human verifies, dates, and corrects in public. Tools may help draft; they do not ship unsourced claims. Check the primary links. Fail that test and leave.

Do I need an account?

No. Filters live in this browser and the URL. Share the link. That’s it. Accounts come later only if they earn it — not so we can nurture you about email.

I’m an agency. Where’s multi-client mode?

We tried a client-name CRM on the setup card. It made the product feel like work before it felt useful. Role filters + copy link + one-page brief (optional PDF title) is enough for now. Complexity comes back when the free shelf is habit, not before.

Is the quiet changelog a bug?

No. Quiet means nothing material moved. We don’t invent urgency so the homepage looks “alive.” Sticky risks still show what usually needs a person when the market is still.