Diagnostic reference

Invalid email recipient

How to find a malformed address in a MailApp recipient list in Google Apps Script and fix it before the script sends email.

Updated August 30, 2026

What myFunction reports

Invalid email address in cc: not-an-email

What it means

Apps Script types the cc field as a string, but not every string is a valid recipient list. myFunction checks supported literal values, splits comma-separated addresses, and points to the malformed entry.

Before and after

The code before and after the fix.

Problem 1 changed line

function sendWeeklyReport() {
  MailApp.sendEmail({
    to: 'owner@example.com',
    subject: 'Weekly report',
    body: 'The report is ready.',
    cc: 'ops@example.com, not-an-email',
  });
}

Fixed 1 changed line

function sendWeeklyReport() {
  MailApp.sendEmail({
    to: 'owner@example.com',
    subject: 'Weekly report',
    body: 'The report is ready.',
    cc: 'ops@example.com, editor@example.com',
  });
}

What myFunction does

Points to the invalid entry inside the comma-separated recipient string.
Marks only the malformed entry, not the valid addresses in the same field.

Check before you apply

Choose the correct replacement address. myFunction does not guess recipients.
myFunction checks literal values only. Addresses built at runtime are not checked, because their final text is not visible while you edit.
Run the function in Apps Script and check the email that arrives.