docs: port still-relevant WHMCS KB articles to the dedicated KB

First step of retiring the WHMCS knowledgebase in favour of
kb.anhonesthost.com. Ports the four articles that are still accurate and
product-agnostic, into three new top-level sections:

- domains/  — transferring a domain, flushing a local DNS cache
- email/    — why we filter outbound mail
- support/  — remote support via RustDesk

Content was refreshed rather than copied verbatim:
- RustDesk download links were pinned to 1.3.8; now point at /releases/latest
  (current is 1.4.9). API server switched to https, which the relay serves.
- macOS DNS flush gained the killall mDNSResponder step, without which the
  documented command usually appears to do nothing.
- The nameserver list was deliberately not ported — this KB points customers
  at Dashboard → Server Information instead of hardcoding per-server values.
- Added an anti-social-engineering warning to the remote-support page.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/content/docs/email/outbound-spam-filtering.mdx

@@ -0,0 +1,53 @@
+---
+title: Why we filter outbound email
+description: We scan mail leaving our servers, not just mail arriving. Here's why, and what to do if a legitimate message gets held.
+sidebar:
+  order: 1
+---
+
+import { Aside } from '@astrojs/starlight/components';
+import Support from '~/content/partials/support-link.mdx';
+
+Most hosts filter the mail arriving at your inbox. We also filter the mail **leaving** our servers — which occasionally surprises people, so here's the reasoning.
+
+## Why outbound filtering exists
+
+Large mail providers — Gmail, Outlook / Hotmail, Yahoo and others — judge mail by the **server it came from**, not by who wrote it. If spam leaves our servers, we're recorded as the sender, and our server's address can land on a blocklist.
+
+That matters even when the spam isn't ours to begin with. A forwarder is the classic case: someone sends spam to an address on our server that forwards to a Gmail account. We didn't originate it, but as far as Gmail is concerned, we handed it over — so it counts against us.
+
+Once a server is blocklisted, the consequences land on everyone hosted there. Most lists delist within a few days, but some take **up to a year**, and repeated or severe listings can attract longer penalties or a refusal to delist at all. During that time, mail from every customer on the server is at risk of being rejected or sent to spam.
+
+Outbound filtering is how we keep that from happening. It's not a common feature among hosting providers, and we think it should be.
+
+## When legitimate mail gets caught
+
+No filter is perfect. Marketing and bulk mail is the most likely to be held, since it shares many characteristics with the mail the filter is built to stop.
+
+If a message you sent didn't arrive, [open a ticket](https://secure.anhonesthost.com/submitticket.php) with:
+
+- the **subject line** of the message;
+- the **from** address;
+- the **destination** address;
+- roughly **when** you sent it.
+
+That's enough for us to find it in the logs, release it if it's legitimate, and tune the filter so similar messages pass in future.
+
+<Aside type="tip">
+  Sending genuine bulk or marketing email? Tell us before you start. We can make sure your sending domain is set up so it isn't mistaken for spam — and we'll go over the authentication records and consent rules that keep it landing in inboxes.
+</Aside>
+
+## Helping your mail get delivered
+
+Filtering aside, most delivery problems come down to authentication. Mail from your domain should have **SPF** and **DKIM** records in DNS so receiving servers can verify it really came from you.
+
+If your domain uses our nameservers, we add an SPF record automatically when you add the domain, and your DKIM records are listed in WHP under **Email → Email Domains (DNS)**. If your DNS lives elsewhere, you'll need to copy those records to your DNS provider yourself — see [Create an email account](/whp/how-to/create-an-email-account/).
+
+## Related
+
+- [Create an email account](/whp/how-to/create-an-email-account/)
+- [Manage DNS records](/whp/how-to/manage-dns-records/)
+
+## Still stuck?
+
+<Support />