> ## Documentation Index
> Fetch the complete documentation index at: https://docs.custral.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Deliverability

> SPF, DKIM, DMARC, sender reputation, and how to manage sending domains in Custral.

Deliverability is whether your email actually reaches the inbox. Custral inherits the deliverability profile of the underlying mailbox you've connected. Custral does not relay through its own SMTP, so your reputation stays with you. The goal of this guide is to surface the levers that affect inbox placement and the diagnostics Custral exposes.

## The three records that matter

<Steps>
  <Step title="SPF, who is allowed to send for your domain">
    A TXT record on your domain that lists the IPs / providers permitted to send mail with your `From:` address. Most issues come from missing `include:` entries when adding a new sending provider.
  </Step>

  <Step title="DKIM, cryptographic signature on each message">
    A public key published on a `._domainkey.` subdomain. Each outbound message is signed; receivers verify the signature against the published key. Without DKIM, forwarded messages are routinely rejected.
  </Step>

  <Step title="DMARC. What receivers should do when SPF or DKIM fails">
    A TXT record at `_dmarc.<domain>` that tells receiving servers whether to quarantine or reject mail that fails alignment. A `p=reject` policy is strict but is increasingly required by major mailbox providers.
  </Step>
</Steps>

## Diagnostics

Custral surfaces deliverability signals on each Channel:

* The last 50 inbound delivery reports (provider IDs + status).
* Per-domain bounce and complaint rates over the last 30 days.
* Whether the channel's domain has SPF / DKIM / DMARC published correctly (a DNS check refreshed daily).

## Sender reputation

Reputation is per-sending-IP and per-domain. Sending from a brand-new domain with high volume is the fastest way to be flagged as a spammer, warm a domain by ramping volume gradually over 2-4 weeks.

## What to do when delivery degrades

<Warning>
  If your bounce rate climbs above \~5% or your complaint rate above 0.1%, mailbox providers will start to throttle.
  Pause outbound sequences, audit your list for stale addresses, and remove anyone who hasn't engaged in 90+ days.
</Warning>

* Remove suppressed addresses (see [Suppressions](/comms/suppressions/overview)).
* Review your unsubscribe link. Every campaign email must carry one.
* Slow down sending and let reputation recover before resuming.

***

## Configuring domains in Custral

Sending domains are managed from the **Domains** settings screen. It has up to two tabs:

<CardGroup cols={2}>
  <Card title="Active Domains" icon="globe">
    A card per domain showing verification status, mailboxes, DNS setup, health score, and per-domain actions.
  </Card>

  <Card title="Health & Deliverability" icon="chart-line">
    Per-channel health scores and Gmail / Outlook inbox-placement bars. Admin-only.
  </Card>
</CardGroup>

<Note>
  Adding domains (**Buy Domain** / **Connect Existing Domains**) and the **Health & Deliverability** tab are
  **admin-only**. They appear only when your account has admin access. Non-admins still see the Active Domains list and
  can verify, add mailboxes, and view DNS records.
</Note>

### Adding a domain

<Tabs>
  <Tab title="Buy a new domain">
    From the header, click **Buy Domain**. Search for a domain name; results show **Available** / **Unavailable** with a per-domain **Buy** action priced in credits. Purchasing registers the domain as a **Custral Managed** domain and begins configuration.

    <Info>
      A newly purchased domain shows a **Registering** state while registration completes. DNS setup becomes available once registration finishes (usually 5–30 minutes).
    </Info>
  </Tab>

  <Tab title="Connect a domain you own">
    Click **Connect Existing Domains**. Enter one or more domains (one per line or comma-separated). If any are found in your linked AWS account, they're listed with a checkbox and expiry date so you can select them, and DNS is configured automatically. Domains not in AWS are connected as **External** and require manual DNS records.
  </Tab>
</Tabs>

### The domain card (Active Domains)

Each domain card surfaces:

| Element         | What it shows                                                                                                                              |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| Domain + source | The domain name, labeled **Custral Managed** or **External**. A **Primary** badge marks the primary domain.                                |
| Status badge    | `Verified` (active), `Pending Verification`, `Not Verified`, `Registering`, `Suspended`, or `Warming`.                                     |
| Mailboxes       | Expandable count of email mailboxes on the domain, each tagged **Managed** or **Connected** (and **Calendar** if a calendar is connected). |
| DNS box         | "DNS Setup Required" (before verification) or "DNS Configuration" (after), with an info icon to open the records.                          |
| Expiry          | For registered domains, the expiry date.                                                                                                   |
| Health Score    | A percentage bar (green > 80%, orange > 50%, red below).                                                                                   |

### Card actions

<AccordionGroup>
  <Accordion title="Verify Domain / Sync Status">
    Re-checks verification with the provider. Before verification this is a **Verify Domain** button; once active it
    becomes a **Sync Status** refresh icon. Verification depends on DNS propagation, so it may report "still pending."
  </Accordion>

  <Accordion title="Add Mailbox">Opens the **Add Mailbox** modal (see below).</Accordion>

  <Accordion title="Set as Primary">
    From the card's overflow menu (⋮), makes this the primary sending domain.
  </Accordion>

  <Accordion title="View AWS DNS Settings">
    For Custral-managed domains, opens a viewer of the current DNS record set, with a **Clear DNS** action.
  </Accordion>

  <Accordion title="Delete Domain">
    Admin-only, in the overflow menu. Disabled for the primary domain and for any domain that still has mailboxes.
    Delete its mailboxes first.
  </Accordion>
</AccordionGroup>

### DNS records & sync

The DNS info icon opens **DNS Records for \<domain>**, listing each record's **type**, **name**, **value** (with **Copy Value**), and a verification **status** badge. DNS records are fetched on demand when the modal opens. Add these records at your registrar (Google, GoDaddy, Cloudflare, etc.) to verify ownership and enable sending.

For **Custral-managed** domains, the records modal also offers:

| Action            | What it does                                                                                                |
| ----------------- | ----------------------------------------------------------------------------------------------------------- |
| Inject DNS to AWS | Writes the required records into the domain's managed DNS zone (and may also update registrar nameservers). |
| Sync Nameservers  | Points the registrar's nameservers at the managed DNS zone (propagation can take up to 48 hours).           |
| Clear DNS         | Removes MX, TXT, and other non-system records from the managed DNS zone. Use with care.                     |
| Verify Now        | Re-runs the verification check and refreshes the list.                                                      |

<Warning>
  **Clear DNS** removes records from the managed DNS zone and can break sending and verification for that domain. Only
  use it when you intend to rebuild the zone.
</Warning>

### Adding a mailbox

The **Add Mailbox** modal creates a new Custral-managed mailbox on the domain (it includes a calendar reachable from the calendar UI):

* **Account Name**: a display label for the mailbox.
* **Local Part**: the part before `@<domain>` (the modal shows the full address inline).
* **Assign to User (Optional)**: pick an owner.

To edit an existing mailbox, use its overflow menu → **Edit / Assign User**, which exposes the mailbox name / email and owner, **Manage Assignments** (share the inbox with additional users / teams), routing rules, and a **connection health** panel with a **Test connection** button. Use it when sends or syncs look stuck.

### Warming settings (deliverability ramp)

Open a mailbox's overflow menu → **Warming Settings**. Every user sees **Account Name**, **Sender Display Name** (the name recipients see on warming emails), and **Enable Email Warming** (the on/off toggle).

<Note>
  Volume limits and the ramp rate are managed by Custral rather than set per mailbox. Warming works best on a schedule
  tuned to a domain's age and reputation. Ask [support](mailto:hello@custral.com) if you need a ramp faster or slower
  than the default.
</Note>

### Health & Deliverability tab

This admin-only tab shows, per domain, each channel's **Health** score and **Gmail** / **Outlook** inbox-placement percentages (inbox vs. total), plus a **Warming Active** badge and today's warming usage vs. the current limit when warming is on.

## Troubleshooting

| Symptom                                                  | Likely cause                                                 | What to check                                                                                                               |
| -------------------------------------------------------- | ------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------- |
| Domain stuck on **Registering**                          | Registration still in progress                               | Wait 5–30 minutes; DNS setup unlocks once registration completes.                                                           |
| Domain stays **Pending Verification** / **Not Verified** | DNS records not added or not yet propagated                  | Open DNS Records, add them at your registrar, then click **Verify Now** / **Verify Domain**. Propagation can take hours.    |
| DNS Records modal shows "No DNS records available yet"   | Records not generated yet (often a domain still registering) | Wait for registration to finish, then reopen the modal.                                                                     |
| Custral-managed domain not verifying after Inject DNS    | Registrar nameservers not pointed at the managed DNS zone    | Use **Sync Nameservers** (Custral-managed domains); allow up to 48h to propagate.                                           |
| Can't add **Buy Domain** / see Health tab                | You're not an admin                                          | Those controls are admin-only; ask a workspace admin.                                                                       |
| **Delete Domain** is disabled                            | It's the primary domain or still has mailboxes               | Set a different domain primary and / or delete its mailboxes first.                                                         |
| Sends or syncs from a mailbox look stuck                 | The mailbox connection expired, was revoked, or is invalid   | Edit the mailbox → **Test connection**; reconnect the mailbox if it reports a problem.                                      |
| Low inbox placement on the Health tab                    | Poor reputation or warming not ramped                        | Enable / continue warming, slow sending, and clear suppressed addresses (see [Suppressions](/comms/suppressions/overview)). |

## Related

* [Suppressions](/comms/suppressions/overview): keep bounces and complaints off your lists.
* [Email overview](/comms/email/overview)
* [Calendar overview](/comms/calendar/overview)


## Related topics

- [Troubleshooting](/comms/deliverability/troubleshooting.md)
- [Suppressions](/comms/suppressions/overview.md)
- [Nylas](/integrations/nylas.md)
- [Voice & Calls](/comms/voice/overview.md)
- [A2P 10DLC Registration](/comms/sms/a2p-registration.md)