.

src/index.tsx

@@ -45,12 +45,11 @@ export const emailServer = new SMTPServer({
     (async () => {
       const email = await mailparser.simpleParser(stream);
       const { entry } = Entry({
-        title: email.subject,
-        author: email.from.text,
-        // FIXME: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/43234 / typeof email.html !== "boolean" => email.html !== false
-        ...(typeof email.html === "boolean"
-          ? { html: false, content: email.text ?? "" }
-          : { content: email.html })
+        title: email.subject ?? "",
+        author: email.from?.text ?? "",
+        ...(typeof email.html === "string"
+          ? { content: email.html }
+          : { html: false, content: email.text ?? "" })
       });
       for (const { address } of session.envelope.rcptTo) {
         const match = address.match(/^(\w+)@kill-the-newsletter.com$/);

src/test.ts

@@ -80,6 +80,17 @@ describe("receive email", () => {
       html: "<p>HTML content</p>"
     });
   });
+
+  test("missing from", async () => {
+    const identifier = await createFeed();
+    await emailClient.sendMail({
+      to: `${identifier}@kill-the-newsletter.com`,
+      subject: "New Message",
+      html: "<p>HTML content</p>"
+    });
+    const feed = await getFeed(identifier);
+    expect(feed).toMatch("HTML content");
+  });
 });
 
 afterAll(() => {