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 inspects supported literal values, splits comma-delimited addresses, and points to the malformed entry.

Before and after

See the change before you make it.

Problem

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

Safer version

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

What the assist changes

Points to the invalid entry inside the comma-separated recipient string.
Leaves valid addresses in the same field distinguishable from the malformed value.
Reports against literal values only, where the extension can verify the actual text.

What stays with you

Choose the correct replacement address; myFunction does not guess recipients.
Values assembled at runtime are left alone because their final recipients are not visible while editing.
Running the function and confirming the resulting email remain in Apps Script.