fix: keep an escaped quote in a pasted display name from splitting off a recipient

src/lib/__tests__/recipients.test.ts

@@ -38,6 +38,23 @@ describe('splitRecipients', () => {
   it('keeps RFC 5322 groups as one entry', () => {
     expect(splitRecipients('Team: a@x.com, b@y.com;, c@z.com')).toEqual(['Team: a@x.com, b@y.com;', 'c@z.com']);
   });
+
+  it('does not take an escaped quote in a display name as the closing one', () => {
+    expect(splitRecipients('"Support\\", ceo@corp.example, \\"x" <s@x.com>, b@y.com'))
+      .toEqual(['"Support\\", ceo@corp.example, \\"x" <s@x.com>', 'b@y.com']);
+  });
+
+  it('does not take an escaped quote as closing when an unclosed angle bracket looks ahead', () => {
+    expect(splitRecipients('John <j@x.com, "a\\"> b" <b@y.com>')).toEqual(['John <j@x.com', '"a\\"> b" <b@y.com>']);
+  });
+});
+
+describe('splitPastedRecipients with an escaped quote (composer paste)', () => {
+  it('adds no extra recipient from inside a display name', () => {
+    const { valid, invalid } = splitPastedRecipients('"Support\\", ceo@corp.example, \\"x" <s@x.com>, b@y.com');
+    expect(valid.map((r) => r.email)).toEqual(['s@x.com', 'b@y.com']);
+    expect(invalid).toEqual([]);
+  });
 });
 
 describe('parseRecipient', () => {

src/lib/recipients.ts

@@ -58,7 +58,9 @@ function angleRunCloses(value: string, from: number): boolean {
   let inQuotes = false;
   for (let i = from + 1; i < value.length; i++) {
     const ch = value[i];
-    if (ch === '"') inQuotes = !inQuotes;
+    // A quoted-pair (`\"`) never closes the quote.
+    if (inQuotes && ch === '\\') i++;
+    else if (ch === '"') inQuotes = !inQuotes;
     else if (inQuotes) continue;
     else if (ch === '>') return true;
     else if (ch === '<') return false;
@@ -84,7 +86,13 @@ export function splitRecipients(value: string, separators = ','): string[] {
   let inGroup = false;
   for (let i = 0; i < value.length; i++) {
     const ch = value[i];
-    if (ch === '"') {
+    if (inQuotes && ch === '\\' && i + 1 < value.length) {
+      // A quoted-pair: a `"` in a display name is written `\"`. Taking it as
+      // the closing quote let a name like `Support", ceo@corp.example, "x`
+      // split into an extra recipient (webmail lib/email-composer-utils.ts).
+      current += ch + value[i + 1];
+      i++;
+    } else if (ch === '"') {
       inQuotes = !inQuotes;
       current += ch;
     } else if (ch === '<' && !inQuotes) {