Keep a published rule when some invitation emails already went out, and only set Reply-To when the inviter address is a mailbox.

app/api/invites/rule-stakeholder/resend/route.ts

@@ -9,6 +9,7 @@ import { sendRuleStakeholderInviteEmail } from "../../../../../lib/server/mail";
 import { apiRoute } from "../../../../../lib/server/apiRoute";
 import { logRouteError } from "../../../../../lib/server/requestId";
 import { stakeholderInviteVerifyUrl } from "../../../../../lib/server/ruleStakeholderInviteOps";
+import { RULE_STAKEHOLDER_INVITER_FALLBACK } from "../../../../../lib/server/ruleStakeholderInviteMail";
 import { STAKEHOLDER_INVITE_TTL_MS } from "../../../../../lib/server/ruleStakeholders";
 import {
   dbUnavailable,
@@ -102,7 +103,9 @@ export const POST = apiRoute(
     const origin = getPublicOrigin(request);
     const verifyUrl = stakeholderInviteVerifyUrl(origin, nextToken);
     const inviterEmail =
-      row.invitedBy?.email ?? row.rule.user?.email ?? "CommunityRule";
+      row.invitedBy?.email ??
+      row.rule.user?.email ??
+      RULE_STAKEHOLDER_INVITER_FALLBACK;
     try {
       await sendRuleStakeholderInviteEmail({
         to: row.email,

app/api/rules/route.ts

@@ -205,9 +205,10 @@ export const POST = apiRoute(
     });
 
     const origin = getPublicOrigin(request);
-    try {
-      for (const inv of invites) {
-        const verifyUrl = stakeholderInviteVerifyUrl(origin, inv.token);
+    let sent = 0;
+    for (const inv of invites) {
+      const verifyUrl = stakeholderInviteVerifyUrl(origin, inv.token);
+      try {
         await sendRuleStakeholderInviteEmail({
           to: inv.email,
           verifyUrl,
@@ -217,11 +218,15 @@ export const POST = apiRoute(
           summary,
           document,
         });
+        sent += 1;
+      } catch (err) {
+        logRouteError("rules.publish", requestId, err, {
+          phase: "sendRuleStakeholderInviteEmail",
+          email: inv.email,
+        });
       }
-    } catch (err) {
-      logRouteError("rules.publish", requestId, err, {
-        phase: "sendRuleStakeholderInviteEmail",
-      });
+    }
+    if (sent === 0) {
       try {
         await prisma.publishedRule.delete({ where: { id: rule.id } });
       } catch (delErr) {

lib/server/mail.ts

@@ -8,6 +8,7 @@ import {
 import { getSmtpUrl } from "./env";
 import {
   buildRuleStakeholderInviteMail,
+  stakeholderInviteReplyTo,
   type RuleStakeholderInviteMailInput,
 } from "./ruleStakeholderInviteMail";
 
@@ -102,12 +103,13 @@ export async function sendRuleStakeholderInviteEmail(
   input: RuleStakeholderInviteMailInput,
 ): Promise<void> {
   const { subject, text, html } = buildRuleStakeholderInviteMail(input);
+  const replyTo = stakeholderInviteReplyTo(input.inviterEmail);
   await sendHtmlMail({
     to: input.to,
     subject,
     text,
     html,
-    replyTo: input.inviterEmail.trim().toLowerCase(),
+    ...(replyTo ? { replyTo } : {}),
     devLog: `[dev] Rule stakeholder invite (${input.communityName}) for ${input.to}: ${input.verifyUrl}`,
   });
 }

lib/server/ruleStakeholderInviteMail.ts

@@ -8,6 +8,28 @@ import {
 
 export const RULE_STAKEHOLDER_INVITE_LOGO_PATH = getAssetPath(ASSETS.LOGO_MARK);
 
+/** Letter name when neither the inviter nor the rule owner has an email. */
+export const RULE_STAKEHOLDER_INVITER_FALLBACK = "Someone from this community";
+
+const MAILBOX_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+
+/** Reply-To only when the inviter value is a mailbox. */
+export function stakeholderInviteReplyTo(
+  inviterEmail: string,
+): string | undefined {
+  const mailbox = inviterEmail.trim().toLowerCase();
+  if (!MAILBOX_PATTERN.test(mailbox)) return undefined;
+  return mailbox;
+}
+
+/** Email addresses stay lowercase; any other label is kept for the letter. */
+export function stakeholderInviteInviterLabel(inviterEmail: string): string {
+  const replyTo = stakeholderInviteReplyTo(inviterEmail);
+  if (replyTo) return replyTo;
+  const trimmed = inviterEmail.trim();
+  return trimmed.length > 0 ? trimmed : RULE_STAKEHOLDER_INVITER_FALLBACK;
+}
+
 const PREVIEW_TEXT =
   "It covers how they talk, who belongs, how they decide and what happens when they disagree.";
 
@@ -44,7 +66,7 @@ export function buildRuleStakeholderInviteMail(
   input: RuleStakeholderInviteMailInput,
 ): RuleStakeholderInviteMailContent {
   const communityName = input.communityName.trim() || "A community";
-  const inviterEmail = input.inviterEmail.trim().toLowerCase();
+  const inviterEmail = stakeholderInviteInviterLabel(input.inviterEmail);
   const origin = input.origin.replace(/\/$/, "");
   const verifyUrl = input.verifyUrl;
   const copyUrl = ruleStakeholderInviteCopyUrl(verifyUrl);

tests/unit/ruleStakeholderInviteMail.test.ts

@@ -1,13 +1,47 @@
 import { describe, expect, it } from "vitest";
 import {
   RULE_STAKEHOLDER_INVITE_LOGO_PATH,
+  RULE_STAKEHOLDER_INVITER_FALLBACK,
   buildRuleStakeholderInviteMail,
   ruleStakeholderInviteCopyUrl,
+  stakeholderInviteInviterLabel,
+  stakeholderInviteReplyTo,
 } from "../../lib/server/ruleStakeholderInviteMail";
 
 const VERIFY_URL =
   "https://communityrule.info/api/invites/rule-stakeholder/verify?token=abc";
 
+describe("stakeholder invite reply address", () => {
+  it("uses a mailbox as Reply-To and keeps a missing address out of the header", () => {
+    expect(stakeholderInviteReplyTo("  Maya@Example.org ")).toBe(
+      "maya@example.org",
+    );
+    expect(stakeholderInviteReplyTo(RULE_STAKEHOLDER_INVITER_FALLBACK)).toBe(
+      undefined,
+    );
+    expect(stakeholderInviteReplyTo("CommunityRule")).toBe(undefined);
+  });
+
+  it("names a missing inviter without turning the label into an address", () => {
+    expect(stakeholderInviteInviterLabel("")).toBe(
+      RULE_STAKEHOLDER_INVITER_FALLBACK,
+    );
+    expect(stakeholderInviteInviterLabel("Maya@Example.org")).toBe(
+      "maya@example.org",
+    );
+    const mail = buildRuleStakeholderInviteMail({
+      to: "rosa@example.org",
+      verifyUrl: VERIFY_URL,
+      origin: "https://communityrule.info",
+      communityName: "Juniper Street Food Share",
+      inviterEmail: RULE_STAKEHOLDER_INVITER_FALLBACK,
+    });
+    expect(mail.text).toContain(
+      `${RULE_STAKEHOLDER_INVITER_FALLBACK} sent the invitation.`,
+    );
+  });
+});
+
 describe("ruleStakeholderInviteCopyUrl", () => {
   it("adds copy=1 to the invitation link", () => {
     expect(ruleStakeholderInviteCopyUrl(VERIFY_URL)).toBe(

tests/unit/ruleStakeholderInviteResendExpiredRoute.test.ts

@@ -41,6 +41,7 @@ vi.mock("../../lib/server/rateLimit", () => ({
     rateLimitKeyMock(key, minIntervalMs),
 }));
 
+import { RULE_STAKEHOLDER_INVITER_FALLBACK } from "../../lib/server/ruleStakeholderInviteMail";
 import { POST } from "../../app/api/invites/rule-stakeholder/resend/route";
 
 beforeEach(() => {
@@ -109,4 +110,39 @@ describe("POST /api/invites/rule-stakeholder/resend", () => {
       }),
     );
   });
+
+  it("does not use a fake mailbox when the inviter and owner have no email", async () => {
+    findUniqueMock.mockResolvedValueOnce({
+      id: "st-1",
+      email: "inv@example.com",
+      inviteTokenHash: "hash-old",
+      inviteExpiresAt: new Date(Date.now() - 60_000),
+      invitedBy: null,
+      rule: {
+        title: "Juniper Street Food Share",
+        summary: null,
+        document: {},
+        user: { email: null },
+      },
+    });
+
+    const res = await POST(
+      new NextRequest("https://x.test/api/invites/rule-stakeholder/resend", {
+        method: "POST",
+        body: JSON.stringify({
+          token: "a".repeat(12),
+          email: "inv@example.com",
+        }),
+        headers: { "content-type": "application/json" },
+      }),
+      undefined,
+    );
+
+    expect(res.status).toBe(200);
+    expect(sendInviteMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        inviterEmail: RULE_STAKEHOLDER_INVITER_FALLBACK,
+      }),
+    );
+  });
 });

tests/unit/rulesPublishPostRoute.test.ts

@@ -202,6 +202,55 @@ describe("POST /api/rules", () => {
     });
   });
 
+  it("keeps the rule when a later invite send fails after one succeeded", async () => {
+    const created = {
+      id: "rule-partial",
+      title: "Published title",
+      summary: null,
+      createdAt: new Date("2026-01-02T00:00:00.000Z"),
+    };
+    transactionMock.mockImplementation(
+      async (
+        fn: (tx: {
+          publishedRule: { create: typeof vi.fn };
+          ruleStakeholder: { create: typeof vi.fn };
+        }) => Promise<unknown>,
+      ) => {
+        const tx = {
+          publishedRule: {
+            create: vi.fn().mockResolvedValue(created),
+          },
+          ruleStakeholder: {
+            create: vi.fn().mockResolvedValue({}),
+          },
+        };
+        return fn(tx);
+      },
+    );
+    sendInviteMock
+      .mockResolvedValueOnce(undefined)
+      .mockRejectedValueOnce(new Error("smtp down"));
+
+    const res = await POST(
+      new NextRequest("https://x.test/api/rules", {
+        method: "POST",
+        body: JSON.stringify({
+          title: "Published title",
+          summary: null,
+          document: {},
+          stakeholderEmails: ["first@example.com", "second@example.com"],
+        }),
+      }),
+      undefined,
+    );
+
+    expect(res.status).toBe(200);
+    expect(sendInviteMock).toHaveBeenCalledTimes(2);
+    expect(publishedRuleDeleteMock).not.toHaveBeenCalled();
+    const body = (await res.json()) as { rule: { id: string } };
+    expect(body.rule.id).toBe("rule-partial");
+  });
+
   it("creates an unlisted rule when there is no session", async () => {
     getSessionUserMock.mockResolvedValueOnce(null);
     publishedRuleCreateMock.mockResolvedValueOnce({