docs(email): document mail-client autodiscovery + external-DNS records

Reflects the new customer "Mail Client Setup" section on the Email page.

- create-an-email-account.mdx: new "Auto-configure your mail app" section —
  explains clients self-configure from DNS, that domains on our nameservers
  are already set, and the records to add when DNS is hosted elsewhere
  (Cloudflare/GoDaddy/etc.) with the full RFC 6186 record table + screenshot.
  Reframe "Set up your email client" as the manual fallback.
- manage-dns-records.mdx: cross-link "Mail autodiscovery records" subsection.
- New capture-email.ts + whp-email-autodiscovery.png (fleet-redacted: mail
  host shown as <mail-server>.cloud-hosting.io; demo domain kept visible).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/content/docs/whp/how-to/create-an-email-account.mdx

@@ -34,9 +34,41 @@ import Support from '~/content/partials/support-link.mdx';
 
 </Steps>
 
+## Auto-configure your mail app
+
+Most modern mail apps — Outlook, Apple Mail, Thunderbird, and the iOS and Android mail apps — can set themselves up from your domain's DNS. You enter your **full email address** and **password**, and the app finds the right servers, ports, and security settings on its own.
+
+**If your domain uses our nameservers, this already works** — we add the necessary records automatically when you add the domain, so there's nothing for you to do.
+
+### If your DNS is hosted elsewhere
+
+If your domain's DNS lives at another provider (Cloudflare, GoDaddy, Namecheap, and so on), your mail app can't auto-configure until you add a few records there yourself. The Email page builds the exact records for you: open the **Mail Client Setup** section, pick the domain, and copy them in.
+
+![The Mail Client Setup section on the WHP Email page, showing autodiscovery DNS records for a domain](~/assets/screenshots/whp/whp-email-autodiscovery.png)
+
+Add these records to the domain's zone at your DNS provider. The names are **relative to your domain** — most providers fill in the rest automatically, so `autoconfig` becomes `autoconfig.example.com`.
+
+| Type | Name | Priority | Weight | Port | Value |
+| --- | --- | --- | --- | --- | --- |
+| CNAME | `autoconfig` | — | — | — | your mail server |
+| SRV | `_autodiscover._tcp` | 0 | 0 | 443 | your mail server |
+| SRV | `_imaps._tcp` | 0 | 1 | 993 | your mail server |
+| SRV | `_submission._tcp` | 0 | 1 | 587 | your mail server |
+| SRV | `_pop3s._tcp` | 0 | 1 | 995 | your mail server |
+
+Use the **mail server hostname shown in the Mail Client Setup section** as the value — it's the same host your **MX** record points at. The `_pop3s` record is only needed if you read mail over POP3 instead of IMAP. Click **Copy records** to grab them all at once in zone-file format.
+
+<Aside type="tip">
+  If your provider has a proxy toggle (such as Cloudflare's orange cloud), keep these records **DNS only** — proxying them stops mail clients from reading them.
+</Aside>
+
+<Aside type="note">
+  These records only help apps *find* the server. You still create the mailbox in WHP first, and your domain's **MX** record must point at our mail server for mail to be delivered.
+</Aside>
+
 ## Set up your email client
 
-The exact IMAP, POP3, and SMTP hostnames are listed on the Email page — click **Setup Instructions → View Instructions** under **Mail Server Access** for a step-by-step that includes the right hostnames, ports, and security settings for your server.
+Most apps configure themselves from the records above once you enter your address and password. If yours doesn't support that — or you'd rather enter the settings by hand — the exact IMAP, POP3, and SMTP hostnames are listed on the Email page: click **Setup Instructions → View Instructions** under **Mail Server Access** for a step-by-step that includes the right hostnames, ports, and security settings for your server.
 
 The typical settings look like this; substitute the hostname shown in the Setup Instructions:
 

src/content/docs/whp/how-to/manage-dns-records.mdx

@@ -48,6 +48,12 @@ Each domain starts with a standard zone created automatically when the domain wa
   Editing **MX**, **NS**, or the SPF/DKIM **TXT** records can break email delivery or hand DNS control away from us. Only change these if you know exactly what you're doing.
 </Aside>
 
+## Mail autodiscovery records
+
+When we host your DNS, the records that let mail apps configure themselves — an `autoconfig` CNAME plus a set of `_autodiscover` / `_imaps` / `_submission` / `_pop3s` **SRV** records — are already in your zone. You don't need to add them.
+
+If your DNS is at another provider, add them there by hand. WHP builds the exact records for each domain on the **Email** page — see [Auto-configure your mail app](/whp/how-to/create-an-email-account/#auto-configure-your-mail-app).
+
 ## Add a record
 
 <Steps>