Send sign-in mail as HTML so quoted-printable wrapping cannot break the verify URL.

Staging was delivering magic links that looked expired because the token query string was encoded and wrapped in plaintext MIME. Also read rate-limit retry from the API error body, mention spam in the success copy, and document SES relay DNS.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/components/LoginForm.test.tsx

@@ -125,6 +125,7 @@ describe("LoginForm", () => {
       await screen.findByRole("heading", { name: /check your email/i }),
     ).toBeInTheDocument();
     expect(screen.getByText(/we sent a sign-in link/i)).toBeInTheDocument();
+    expect(screen.getByText(/check spam or promotions/i)).toBeInTheDocument();
   });
 
   it("submits a long email without treating length as invalid", async () => {

tests/unit/mail.test.ts

@@ -0,0 +1,103 @@
+import { afterEach, describe, expect, it } from "vitest";
+import nodemailer from "nodemailer";
+import {
+  buildVerifyLinkParts,
+  resolveMailFrom,
+} from "../../lib/server/mail";
+
+const VERIFY_URL =
+  "https://staging.communityrule.info/api/auth/magic-link/verify?token=5IdE_BHowaw-QJj7Rwue7CbB8wDXvYITvnxRb1FGqxA";
+
+function decodeQuotedPrintable(value: string): string {
+  return value
+    .replace(/=\r?\n/g, "")
+    .replace(/=([0-9A-Fa-f]{2})/g, (_, hex: string) =>
+      String.fromCharCode(Number.parseInt(hex, 16)),
+    );
+}
+
+const MAIL_FROM_KEYS = ["SMTP_FROM", "CLOUDRON_MAIL_FROM"] as const;
+const ORIGINAL_FROM = Object.fromEntries(
+  MAIL_FROM_KEYS.map((key) => [key, process.env[key]]),
+) as Record<(typeof MAIL_FROM_KEYS)[number], string | undefined>;
+
+afterEach(() => {
+  for (const key of MAIL_FROM_KEYS) {
+    const original = ORIGINAL_FROM[key];
+    if (original === undefined) delete process.env[key];
+    else process.env[key] = original;
+  }
+});
+
+describe("buildVerifyLinkParts", () => {
+  it("puts the exact verify URL in both text and the HTML href", () => {
+    const { text, html } = buildVerifyLinkParts(
+      VERIFY_URL,
+      "Open this link to sign in (it expires in 15 minutes):",
+      "If you did not request this, you can ignore this email.",
+      "Sign in",
+    );
+    expect(text).toContain(VERIFY_URL);
+    expect(html).toContain(`href="${VERIFY_URL}"`);
+    expect(html).toContain(">Sign in</a>");
+  });
+
+  it("escapes HTML in the intro and href", () => {
+    const { html } = buildVerifyLinkParts(
+      'https://example.test/verify?token=a&b="c"',
+      'View "Rule <beta>"',
+      "Ignore if unexpected.",
+      "Open",
+    );
+    expect(html).toContain("View &quot;Rule &lt;beta&gt;&quot;");
+    expect(html).toContain(
+      'href="https://example.test/verify?token=a&amp;b=&quot;c&quot;"',
+    );
+  });
+});
+
+describe("MIME encoding of verify-link mail", () => {
+  it("keeps a clickable href after quoted-printable encoding", async () => {
+    const { text, html } = buildVerifyLinkParts(
+      VERIFY_URL,
+      "Open this link to sign in (it expires in 15 minutes):",
+      "If you did not request this, you can ignore this email.",
+      "Sign in",
+    );
+    const transporter = nodemailer.createTransport({
+      streamTransport: true,
+      buffer: true,
+      newline: "unix",
+    });
+    const info = await transporter.sendMail({
+      from: "Community Rule <staging.app@communityrule.info>",
+      to: "member@example.com",
+      subject: "Sign in to Community Rule",
+      text,
+      html,
+    });
+    const raw = Buffer.isBuffer(info.message)
+      ? info.message.toString("utf8")
+      : String(info.message);
+    const decoded = decodeQuotedPrintable(raw);
+    expect(decoded).toContain(`href="${VERIFY_URL}"`);
+    expect(decoded).toContain(VERIFY_URL);
+    expect(decoded).not.toContain("token=3D");
+  });
+});
+
+describe("resolveMailFrom", () => {
+  it("prefers SMTP_FROM, then CLOUDRON_MAIL_FROM", () => {
+    delete process.env.SMTP_FROM;
+    delete process.env.CLOUDRON_MAIL_FROM;
+    expect(resolveMailFrom()).toBe("noreply@localhost");
+
+    process.env.CLOUDRON_MAIL_FROM = "staging.app@communityrule.info";
+    expect(resolveMailFrom()).toBe("staging.app@communityrule.info");
+
+    process.env.SMTP_FROM = "Community Rule <hello@communityrule.info>";
+    expect(resolveMailFrom()).toBe(
+      "Community Rule <hello@communityrule.info>",
+    );
+  });
+});