panel-redesign: no report mailbox for the server as a whole

Follows the design commit before it.

  - internal/dmarc: the ingest allow-list is the report address of each
    domain that is on this host and nothing else;
    DefaultHostedReportAddress and DefaultHostedSuggestion are removed.
    Since 1.7.0 the general mailbox dmarc-reports@<hostname> was open
    while no panel-wide default existed; the three-choice scheme had
    left it open always.
  - The DMARC hub's Ingest box shows the form of a hosted address,
    dmarc-reports+<domain>@<hostname>.
  - guide.md: what port 25 accepts.

Evidence: docs/assets/panel-redesign/evidence/dmarc.png re-shot (the
address form wraps after the plus sign in its column at 1440 px).

  go test -count=1 ./internal/dmarc/... ./internal/web/... ./cmd/panel: ok

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/dmarc/addresses.go

@@ -4,7 +4,8 @@ import (
 	"strings"
 )
 
-// DefaultLocalPart is the mailbox local-part for the panel-wide hosted address.
+// DefaultLocalPart is the local part of every hosted address; the domain
+// follows it after a plus sign.
 const DefaultLocalPart = "dmarc-reports"
 
 // HostedReportAddress is the per-domain SelfPost-hosted rua= destination.
@@ -14,11 +15,6 @@ func HostedReportAddress(hostname, domain string) string {
 	return DefaultLocalPart + "+" + domain + "@" + hostname
 }
 
-// DefaultHostedReportAddress is the settings-level hosted rua= when ingest is on.
-func DefaultHostedReportAddress(hostname string) string {
-	return DefaultLocalPart + "@" + strings.ToLower(strings.TrimSpace(hostname))
-}
-
 // IsHostedOnHostname reports whether addr is delivered locally on hostname.
 func IsHostedOnHostname(addr, hostname string) bool {
 	addr = strings.ToLower(strings.TrimSpace(addr))

internal/dmarc/service.go

@@ -64,10 +64,9 @@ func (s *Service) AllowedRecipients() ([]string, error) {
 		seen[addr] = true
 		out = append(out, addr)
 	}
-	// The instance's generic mailbox is always open: it is the address the
-	// guide tells a fresh install to publish. A domain's own report address
-	// opens the mailbox it names, if that is on this host.
-	add(DefaultHostedReportAddress(s.hostname))
+	// Only what a domain has chosen is open: its report address opens the
+	// mailbox it names, if that is on this host. There is no mailbox for the
+	// server as a whole.
 	domains, err := s.store.ListDomains()
 	if err != nil {
 		return nil, err
@@ -101,11 +100,6 @@ func (s *Service) HostedSuggestion(domain string) string {
 	return HostedReportAddress(s.hostname, domain)
 }
 
-// DefaultHostedSuggestion is the settings-level hosted address.
-func (s *Service) DefaultHostedSuggestion() string {
-	return DefaultHostedReportAddress(s.hostname)
-}
-
 // ValidateHostedAddress ensures addr is on this hostname before saving.
 func (s *Service) ValidateHostedAddress(addr string) error {
 	if !IsHostedOnHostname(addr, s.hostname) {

internal/dmarc/service_test.go

@@ -7,8 +7,8 @@ import (
 	"github.com/mixeme/selfpost/internal/store"
 )
 
-// The ingest allow-list is the generic mailbox plus the report address of each
-// domain that points at this host: a new domain (no reports) and a domain
+// The ingest allow-list is the report address of each domain that points at
+// this host, and nothing for the server as a whole: a new domain (no reports) and a domain
 // reporting to another host open nothing of their own.
 func TestAllowedRecipientsFollowTheDomainAddresses(t *testing.T) {
 	st, err := store.Open(t.TempDir() + "/test.db")
@@ -36,7 +36,7 @@ func TestAllowedRecipientsFollowTheDomainAddresses(t *testing.T) {
 	if err != nil {
 		t.Fatalf("AllowedRecipients: %v", err)
 	}
-	want := []string{"dmarc-reports+hosted.example@mail.example.com", "dmarc-reports@mail.example.com", "ops@mail.example.com"}
+	want := []string{"dmarc-reports+hosted.example@mail.example.com", "ops@mail.example.com"}
 	if !reflect.DeepEqual(got, want) {
 		t.Errorf("allowed recipients = %v, want %v", got, want)
 	}

internal/web/handlers/handlers_dmarc_pages_test.go

@@ -49,7 +49,7 @@ func TestDMARCHubShowsIngestAndRecentReports(t *testing.T) {
 	body := getBody(t, s.h.HandleDMARCList, "/outbound/dmarc")
 	has(t, "hub", body,
 		`<h1 class="title is-3">DMARC reports</h1>`, `<h2>Ingest</h2>`, `<span class="tag is-success is-light">ok</span>`,
-		`1 kept · 0 parse failures`, `dmarc-reports@mail.example.org`, `500 reports or 90 days`,
+		`1 kept · 0 parse failures`, `Hosted addresses`, `dmarc-reports&#43;&lt;domain&gt;@mail.example.org`, `500 reports or 90 days`,
 		`<h2>Recent reports</h2>`, `<a href="/outbound/dmarc/domains/1">example.org</a>`, `Outlook.com`,
 		"<td>1\u00a0903</td>", `<span class="tag is-warning is-light">7</span>`, `href="/outbound/dmarc/reports/`+idStr(s.reportID)+`">View</a>`)
 	lacks(t, "hub", body, `None yet`)
@@ -184,7 +184,7 @@ func TestDMARCPagesStayWithinTheViewersDomains(t *testing.T) {
 	has(t, "hub for its administrator", hub.Body.String(), `<h1 class="title is-3">DMARC reports</h1>`, `<h2>Recent reports</h2>`,
 		`<a href="/outbound/dmarc/domains/1">example.org</a>`, `Outlook.com`, `href="/outbound/dmarc/reports/`+idStr(s.reportID)+`"`)
 	lacks(t, "hub for its administrator", hub.Body.String(), "other.example.net", "google.com",
-		`/outbound/dmarc/reports/`+idStr(otherReport)+`"`, `<h2>Ingest</h2>`, `dmarc-reports@mail.example.org`,
+		`/outbound/dmarc/reports/`+idStr(otherReport)+`"`, `<h2>Ingest</h2>`, `Hosted addresses`, `dmarc-reports&#43;&lt;domain&gt;`,
 		`parse failure`, `Last report`, `Retention`)
 
 	// Their own domain and report are theirs, and so is the way back to the hub.

internal/web/handlers/handlers_dmarc_reports.go

@@ -85,7 +85,7 @@ func (h *Handlers) HandleDMARCList(w http.ResponseWriter, r *http.Request) {
 	}
 	in := view.IngestInput{
 		OK: stats.IngestOK, KeptThisWeek: stats.KeptThisWeek, ParseFailures: stats.ParseFailures,
-		Hosted: h.dmarc.DefaultHostedSuggestion(), Host: h.cfg.Hostname,
+		Hosted: dmarc.HostedReportAddress(h.cfg.Hostname, "<domain>"), Host: h.cfg.Hostname,
 		RetentionMax: store.DMARCReportsMaxKeep, RetentionDays: store.DMARCReportsMaxAgeDays,
 	}
 	if stats.LastReceivedAt != nil {

internal/web/view/dmarc.go

@@ -112,7 +112,7 @@ func NewDMARCHub(m Meta, in IngestInput) *DMARCHub {
 		IngestFacts: []Fact{
 			last,
 			{Label: "This week", Value: Plain(FormatCount(int64(in.KeptThisWeek)) + " kept · " + plural(int64(in.ParseFailures), "parse failure", "parse failures"))},
-			{Label: "Hosted address", Value: Plain(in.Hosted), Mono: true},
+			{Label: "Hosted addresses", Value: Plain(in.Hosted), Mono: true},
 			{Label: "Retention", Value: Plain(FormatCount(int64(in.RetentionMax)) + " reports or " + plural(int64(in.RetentionDays), "day", "days"))},
 		},
 		Recent: Box{No: "02", Title: "Recent reports"},

internal/web/view/dmarc_test.go

@@ -12,7 +12,7 @@ func TestDMARCHubShowsIngestAndTheLatestReports(t *testing.T) {
 	pageHas(t, "DMARC reports", out,
 		`<h1 class="title is-3">DMARC reports</h1>`, `<code>rua=</code>`,
 		`<h2>Ingest</h2>`, `<span class="tag is-success is-light">ok</span>`,
-		`<dd>2026-09-21 06:12 UTC</dd>`, `<dd>14 kept · 0 parse failures</dd>`, `<dd class="sp-mono">dmarc@mail.example.org</dd>`, `<dd>500 reports or 90 days</dd>`,
+		`<dd>2026-09-21 06:12 UTC</dd>`, `<dd>14 kept · 0 parse failures</dd>`, `<dt>Hosted addresses</dt>`, `<dd class="sp-mono">dmarc-reports&#43;&lt;domain&gt;@mail.example.org</dd>`, `<dd>500 reports or 90 days</dd>`,
 		`<th>Received, UTC</th>`, `09-21 06:12`, `<a href="/outbound/dmarc/domains/1">example.org</a>`,
 		"<td>1 903</td>", `<span class="tag is-warning is-light">7</span>`, `<td>0</td><td class="sp-actions"><a href="/outbound/dmarc/reports/41">View</a>`,
 	)

internal/web/view/fixtures_test.go

@@ -271,7 +271,7 @@ func outMessageFixture() *OutMessage {
 func dmarcHubFixture() *DMARCHub {
 	p := NewDMARCHub(admin(), IngestInput{
 		OK: true, Last: time.Date(2026, 9, 21, 6, 12, 0, 0, time.UTC), KeptThisWeek: 14, ParseFailures: 0,
-		Hosted: "dmarc@mail.example.org", Host: "mail.example.org", RetentionMax: 500, RetentionDays: 90,
+		Hosted: "dmarc-reports+<domain>@mail.example.org", Host: "mail.example.org", RetentionMax: 500, RetentionDays: 90,
 	})
 	row := func(id int64, at, domain, reporter, window string, pass, fail int) DMARCReportRow {
 		return DMARCReportRow{Received: at, Domain: domain, DomainHref: "/outbound/dmarc/domains/1", Reporter: reporter,