Send as webhook.me.uk, add favicon, share image and SEO tags

Mail now comes from no-reply@webhook.me.uk (DKIM, SPF and DMARC are
set up for it) and the Message-ID uses that domain instead of the
container hostname. The landing page gets a favicon, an Open Graph
image, canonical/OG/Twitter/JSON-LD tags, robots.txt that keeps
crawlers off email URLs, and a sitemap. Footer links to dixon.cx.

.dockerignore

@@ -2,3 +2,4 @@
 !go.mod
 !*.go
 !docs.html
+!static

Dockerfile

@@ -2,11 +2,12 @@ FROM golang:1.26-alpine AS build
 WORKDIR /src
 COPY go.mod ./
 COPY *.go docs.html ./
+COPY static ./static
 RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /webhooks .
 
 FROM gcr.io/distroless/static-debian12:nonroot
 COPY --from=build /webhooks /webhooks
-ENV LISTEN=:8080 SMTP_ADDR=172.17.0.1:25 MAIL_FROM=no-reply@dixon.cx PUBLIC_HOST=webhook.me.uk
+ENV LISTEN=:8080 SMTP_ADDR=172.17.0.1:25 MAIL_FROM=no-reply@webhook.me.uk PUBLIC_HOST=webhook.me.uk
 EXPOSE 8080
 HEALTHCHECK --interval=30s --timeout=3s --start-period=5s CMD ["/webhooks", "-check"]
 ENTRYPOINT ["/webhooks"]

PARSER_PROMPT.md

@@ -354,7 +354,7 @@ Real deliveries over HTTP/2 arrive with lowercase header names. `headers.Get` ha
 |----------|---------|---------|
 | `LISTEN` | `127.0.0.1:8080` | Address to listen on (`:8080` in the container) |
 | `SMTP_ADDR` | `127.0.0.1:25` | SMTP relay (`172.17.0.1:25` in the container, the host's postfix) |
-| `MAIL_FROM` | `no-reply@dixon.cx` | Envelope and From address |
+| `MAIL_FROM` | `no-reply@webhook.me.uk` | Envelope and From address |
 | `PUBLIC_HOST` | `webhook.me.uk` | Host shown in email footers |
 
 ---

README.md

@@ -324,7 +324,7 @@ The image is a static binary on `distroless`, runs as non-root, listens on `:808
 |----------|---------|---------|
 | `LISTEN` | `127.0.0.1:8080` | Address to listen on (`:8080` in the container) |
 | `SMTP_ADDR` | `127.0.0.1:25` | SMTP relay, no auth or TLS (`172.17.0.1:25` in the container) |
-| `MAIL_FROM` | `no-reply@dixon.cx` | Envelope and From address |
+| `MAIL_FROM` | `no-reply@webhook.me.uk` | Envelope and From address |
 | `PUBLIC_HOST` | `webhook.me.uk` | Host shown in email footers |
 
 `/healthz` returns `ok`, and `webhooks -check` exits non-zero if a running instance is unhealthy (used by the image's `HEALTHCHECK`).

docs.html

@@ -1,10 +1,34 @@
 <!DOCTYPE html>
-<html lang="en">
+<html lang="en-GB">
 <head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
-<title>Webhook → Email | {{.Host}}</title>
+<title>Webhook → Email: forward any webhook to your inbox | {{.Canonical}}</title>
 <meta name="description" content="Point any webhook at a URL with your email in it. Get the whole request in your inbox. That's it. That's the product.">
+<link rel="canonical" href="https://{{.Canonical}}/">
+<meta name="robots" content="index, follow">
+<meta name="author" content="Andy Dixon">
+<meta name="theme-color" content="#0047ab">
+<link rel="icon" href="/favicon.svg" type="image/svg+xml">
+<link rel="icon" href="/favicon.ico" sizes="16x16 32x32 48x48">
+<link rel="apple-touch-icon" href="/apple-touch-icon.png">
+<meta property="og:type" content="website">
+<meta property="og:site_name" content="webhook→email">
+<meta property="og:title" content="Webhooks. Straight to your inbox.">
+<meta property="og:description" content="Point any webhook at a URL with your email in it. Get the whole request in your inbox. No signup, no dashboard.">
+<meta property="og:url" content="https://{{.Canonical}}/">
+<meta property="og:image" content="https://{{.Canonical}}/og.png">
+<meta property="og:image:width" content="1200">
+<meta property="og:image:height" content="630">
+<meta property="og:image:alt" content="Webhooks. Straight to your inbox. https://{{.Canonical}}/you%40example.com">
+<meta property="og:locale" content="en_GB">
+<meta name="twitter:card" content="summary_large_image">
+<meta name="twitter:title" content="Webhooks. Straight to your inbox.">
+<meta name="twitter:description" content="Point any webhook at a URL with your email in it. Get the whole request in your inbox. No signup, no dashboard.">
+<meta name="twitter:image" content="https://{{.Canonical}}/og.png">
+<script type="application/ld+json">
+{"@context":"https://schema.org","@type":"WebApplication","name":"webhook→email","url":"https://{{.Canonical}}/","description":"Forward any webhook to your inbox as a formatted email. Parsers for GitHub, Grafana, JSON and Webex Interact.","applicationCategory":"DeveloperApplication","operatingSystem":"Any","isAccessibleForFree":true,"offers":{"@type":"Offer","price":"0","priceCurrency":"GBP"},"author":{"@type":"Person","name":"Andy Dixon","url":"https://dixon.cx/"}}
+</script>
 <style>
 :root{
   --bg:#ffffff;--panel:#f6f8fc;--line:#e3e7ef;
@@ -250,7 +274,7 @@ requests.post(
 
 <footer>
   <div>Built with Go and ADHD medication. Not necessarily in that order.</div>
-  <div>© 2025–2026 Andy Dixon · <a href="https://{{.Host}}/">{{.Host}}</a></div>
+  <div>© 2025–2026 Andy Dixon · <a href="https://dixon.cx/">dixon.cx</a></div>
 </footer>
 
 </div>

mail.go

@@ -6,12 +6,13 @@ import (
 	"mime/quotedprintable"
 	"net/smtp"
 	"os"
+	"strings"
 	"time"
 )
 
 var (
 	smtpAddr = envOr("SMTP_ADDR", "127.0.0.1:25")
-	mailFrom = envOr("MAIL_FROM", "no-reply@dixon.cx")
+	mailFrom = envOr("MAIL_FROM", "no-reply@webhook.me.uk")
 )
 
 // sendMail is a variable so tests can capture messages instead of sending them.
@@ -43,7 +44,7 @@ func smtpSend(to, subject, htmlBody string) error {
 }
 
 func buildMessage(to, subject, htmlBody string) []byte {
-	host, _ := os.Hostname()
+	host := mailFrom[strings.LastIndex(mailFrom, "@")+1:]
 	var b []byte
 	b = fmt.Appendf(b, "From: Webhook Call <%s>\r\n", mailFrom)
 	b = fmt.Appendf(b, "To: <%s>\r\n", to)

main.go

@@ -8,12 +8,13 @@ package main
 import (
 	"bytes"
 	"context"
-	_ "embed"
+	"embed"
 	"encoding/json"
 	"flag"
 	"fmt"
 	"html/template"
 	"io"
+	"io/fs"
 	"log"
 	"net"
 	"net/http"
@@ -32,6 +33,15 @@ var docsSrc string
 
 var docsTmpl = template.Must(template.New("docs").Parse(docsSrc))
 
+//go:embed static
+var staticFS embed.FS
+
+// assets serves favicons and the share image at the site root.
+var assets = func() http.Handler {
+	sub, _ := fs.Sub(staticFS, "static")
+	return http.FileServerFS(sub)
+}()
+
 const maxBody = 10 << 20 // 10 MB, like PHP's post_max_size
 
 // Meta is the request metadata handed to every parser.
@@ -113,12 +123,25 @@ func handle(w http.ResponseWriter, r *http.Request) {
 	path := strings.Trim(r.URL.Path, "/")
 	if path == "" {
 		w.Header().Set("Content-Type", "text/html; charset=UTF-8")
-		_ = docsTmpl.Execute(w, map[string]string{"Host": r.Host})
+		_ = docsTmpl.Execute(w, map[string]string{"Host": r.Host, "Canonical": hostName})
 		return
 	}
-	if path == "healthz" {
+	switch path {
+	case "healthz":
 		_, _ = io.WriteString(w, "ok\n")
 		return
+	case "favicon.ico", "favicon.svg", "apple-touch-icon.png", "og.png":
+		w.Header().Set("Cache-Control", "public, max-age=604800")
+		assets.ServeHTTP(w, r)
+		return
+	case "robots.txt":
+		w.Header().Set("Content-Type", "text/plain; charset=UTF-8")
+		fmt.Fprintf(w, "User-agent: *\nDisallow: /*%%40\nDisallow: /*@\nSitemap: https://%s/sitemap.xml\n", hostName)
+		return
+	case "sitemap.xml":
+		w.Header().Set("Content-Type", "application/xml; charset=UTF-8")
+		fmt.Fprintf(w, `<?xml version="1.0" encoding="UTF-8"?>`+"\n"+`<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"><url><loc>https://%s/</loc></url></urlset>`+"\n", hostName)
+		return
 	}
 
 	parts := strings.SplitN(path, "/", 3)

static/favicon.svg

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
+  <rect width="64" height="64" rx="14" fill="#0047ab"/>
+  <rect x="10" y="18" width="38" height="28" rx="4" fill="#fff"/>
+  <path d="M12 21l17 13 17-13" fill="none" stroke="#0047ab" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>
+  <circle cx="47" cy="45" r="12" fill="#0a0a0a" stroke="#0047ab" stroke-width="3"/>
+  <path d="M41 45h11m-4-4.5 4.5 4.5-4.5 4.5" fill="none" stroke="#fff" stroke-width="3" stroke-linecap="round" stroke-linejoin="round"/>
+</svg>