> For the complete documentation index, see [llms.txt](https://docs.11x.ai/llms.txt).
> Use it to discover all available pages before exploring further.

# Mailbox health and deliverability

11x treats deliverability as core infrastructure - automatic domain setup, warm-up, health monitoring, rotation of degraded domains, and inbox placement testing.


11x treats deliverability as **core infrastructure**, not a setting. It configures **DKIM, DMARC, and SPF** automatically, **warms domains automatically**, monitors **mailbox health in real time**, and when a domain's health declines it is **pulled from sending and rotated out for a warm replacement**. Inbox placement is tested before volume goes out, and blacklisting triggers automatic pausing and cooldown.

<Callout kind="tip">
The reason this is bundled rather than sold separately: excellent messaging is worth nothing if it lands in spam. Tools that ask you to bring your own mailboxes push this entire discipline onto you.
</Callout>

## What's managed automatically

| Capability | Behaviour |
| --- | --- |
| **Domain authentication** | DKIM, DMARC, and SPF configured automatically |
| **Warm-up** | Domains warmed automatically rather than manually ramped |
| **Health monitoring** | Mailbox health tracked in real time |
| **Rotation** | A domain whose health dips is pulled from sending and replaced with a warm one |
| **Placement testing** | Tests whether mail hits primary, promotions, or spam *before* volume goes out |
| **Blacklist detection** | Detects flagging, pauses sending, cools down affected mailboxes; recovery starts automatically |
| **Capacity** | Private sending IPs with capacity tracking, so volume scales cleanly |

<Callout kind="info">
Placement testing before volume is the highest-value item here. It converts deliverability from something you discover retrospectively into something you know in advance.
</Callout>

## Message construction

Deliverability is also affected by how messages are built. 11x defaults to:

- **Plain text**, with no tracking pixels or heavy formatting
- **Every message unique** — no two emails look the same

<Callout kind="alert">
Identical bulk-looking mail is a spam signal in itself. Per-prospect generation helps deliverability, not just response rates — which is a second reason [AI personalization](/alice/ai-personalization) matters.
</Callout>

## What you still own

Automation covers infrastructure. These remain yours:

| Yours | Why |
| --- | --- |
| **Choosing a dedicated sending domain** | Isolates outbound reputation from corporate mail |
| **Verifying DNS independently** | Trust but verify — see the tools below |
| **Targeting quality** | Complaints come from reaching the wrong people, and no infrastructure fixes that |
| **Volume discipline** | Don't override pacing because early results look good |

Verify with the free 11x tools: [domain health](https://www.11x.ai/tools/domain-health-checker) · [SPF](https://www.11x.ai/tools/spf-record-checker) · [DKIM](https://www.11x.ai/tools/dkim-checker) · [DMARC](https://www.11x.ai/tools/dmarc-checker) · [blacklist](https://www.11x.ai/tools/email-blacklist-checker) · [Google Postmaster](https://www.11x.ai/tools/google-postmaster-health-check)

## Metrics to watch

| Metric | Want | If it slips |
| --- | --- | --- |
| **Inbox placement** | Stable or improving, primary folder | Hold volume immediately |
| **Bounce rate** | Near zero | List quality — stop and fix the data source |
| **Complaint rate** | Effectively zero | Targeting — tighten the ICP now |
| **Per-mailbox variance** | Consistent | One bad mailbox drags the whole domain |
| **Domains in rotation** | Stable | Several rotating at once signals a targeting problem |

<Callout kind="alert">
Watch **per-mailbox** figures, not just the domain aggregate. A single mailbox with a high complaint rate can pull down an otherwise healthy domain, and the aggregate hides it.
</Callout>

## When automation isn't enough

Rotation and cooldown protect you from the *symptoms*. They don't fix the cause. If domains are rotating repeatedly:

<Steps>
  <Step title="Stop increasing volume" icon="pause">
    Adding volume to a reputation problem compounds it.
  </Step>
  <Step title="Check complaint rate first" icon="flag">
    Complaints mean you're reaching people who aren't remotely in your market.
  </Step>
  <Step title="Tighten the ICP before touching copy" icon="crosshair">
    A well-targeted mediocre email beats a brilliant email to the wrong person.
  </Step>
  <Step title="Check where contacts came from" icon="database">
    Uploaded lists bounce. Source from the [database](/data/company-and-lead-database) instead.
  </Step>
  <Step title="Then resume ramping" icon="trending-up">
    Gradually, and watch placement daily.
  </Step>
</Steps>

## Frequently Asked Questions

<Expandable title="Why is inbox placement declining across all domains?">
A systemic targeting or volume problem, not an infrastructure one. Check complaint rate and recent volume changes.
</Expandable>

<Expandable title="What should I do if one mailbox is much worse than the others?">
Rotation should handle it, but investigate what that mailbox was sending — usually a specific campaign or segment.
</Expandable>

<Expandable title="Why did we get blacklisted despite automatic monitoring?">
Detection pauses sending and starts cooldown, but blacklisting is usually a *consequence* of complaints or bounces. Fix the cause before the domain returns to rotation.
</Expandable>

<Expandable title="Why is authenticated mail still going to spam?">
Authentication is necessary, not sufficient. Work through the other causes in [why emails go to spam](/help-center/deliverability/why-emails-go-to-spam).
</Expandable>

<Expandable title="Why did sending volume drop without us changing anything?">
A domain was likely pulled for health and a replacement is warming. Check domains in rotation.
</Expandable>

## Next steps

<Columns cols={2}>
  <Card title="Why emails go to spam" icon="triangle-alert" href="/help-center/deliverability/why-emails-go-to-spam" horizontal>
    Diagnosing the eight causes.
  </Card>
  <Card title="Warm up a new domain" icon="thermometer" href="/help-center/deliverability/warm-up-a-new-domain" horizontal>
    What you control during ramp.
  </Card>
  <Card title="Connection boosts" icon="signal" href="/julian/connection-boosts" horizontal>
    The calling equivalent.
  </Card>
  <Card title="Analytics overview" icon="chart-line" href="/analytics/overview" horizontal>
    Where placement is reported.
  </Card>
</Columns>