---
name: "email-deliverability-guardrails"
description: "Check a campaign before it sends: whether the list is sendable, whether the domain is set up, and whether this send will damage the next one."
triggers: ["deliverability", "spam folder", "bounce rate", "email list", "before we send", "warm up", "dmarc"]
version: "1"
---
# Email deliverability guardrails
Use this before any bulk send, and whenever mail starts landing in spam.
## The list is the biggest lever
Most deliverability problems are list problems wearing a technical costume.
- Send only to people who asked. A purchased or scraped list damages the domain
permanently, and no configuration fixes it.
- Judge engagement on clicks, replies, purchases and product activity, never on
opens alone — see below for why opens do not mean what they used to. A
contact with none of those for about six months is a risk, not an audience.
- Never suppress on silence alone. Send one re-permission email first and
suppress only the people who do not answer it. A quiet subscriber who still
buys is not a dead address.
- Remove hard bounces immediately and permanently. Repeated sends to dead
addresses are the clearest spam signal there is.
- Watch complaints, not opens. Open rates have been unreliable since mail
clients started pre-fetching images.
## The setup, checked once
Confirm these exist before the first campaign and never again unless something
breaks: SPF, DKIM, and a DMARC record that is at least at `p=none` and
monitored. Send marketing mail from a subdomain, so a bad campaign cannot take
the company's transactional mail down with it. A new domain sends to its most
engaged people first, in small volumes, for a few weeks.
## The send itself
- One clear sender name that does not change between campaigns.
- A reply-to that a human reads. `noreply@` costs more than it saves.
- A plain-text part that says the same thing as the HTML.
- Link shorteners, single giant images, and `RE:` in a cold subject line all
read as spam because they usually are.
## When mail starts landing in spam
Change one thing at a time and wait. Check in this order: complaint rate, then
list age, then whether the sending volume jumped, then authentication, then
content. Blaming the copy first is the common mistake and rarely the cause.
## What to hand back
A go or a no-go on the send, in the first line, and nothing softer than those
two words. Then:
- **Blockers** — what makes it a no-go, each with the evidence behind it (the
complaint rate, the list's origin, the missing DMARC record) and the specific
correction that clears it.
- **Warnings** — what will not stop this send but will degrade the next one.
- **What you could not check** — the data you would have needed. Say so plainly
rather than passing an unverified item as clear.
A go with three unstated caveats is a no-go that nobody noticed.
## What not to do
Never send to a list the user cannot say the origin of — ask where it came from
and stop if the answer is vague. Never make a deliverability promise, and never
report inbox placement as a fact without seed-test data in front of you.