Sending via the Gmail API from non-primary email address

Question

Greetings Gmail API fans.

I have written some absolutely awesome code, which neatly authenticates and sends email using the Gmail API with JavaScript.

However, even with a brain as big as mine, I have an issue. While emails get sent perfectly using gapi.client.gmail.users.messages.send with a userId set to "me", I cannot get it to send, instead, from an alternate group email address I have associated with my account.

For example, if I try to change the userId to "[email protected]", executing kicks a 401 "Login Required" error, even when that email address is associated with my Gmail account.

Settings screen

Any ideas what's going on?

A smidgeon of code below:

// Stuff gleaned from a form
var headers = {
    'subject': e.data.subject,
    'to': e.data.to,
    'cc': e.data.cc,
    'bcc': e.data.bcc,
    'content-type': 'text/html; charset=utf-8'
};

// grab the email content
message = editor.getContent({format : 'raw'});

// construct the email
var email = '';
for(var header in headers)
    email += header += ': ' + headers[header] + '\r\n';

email += '\r\n' + message;

// This is the bit - changing userId to anything other than 'me' (or the primary email address) kicks error
var sendRequest = gapi.client.gmail.users.messages.send({
    'userId': 'me',
        'resource': {
           'raw': window.btoa(unescape(encodeURIComponent(email))).replace(/\+/g, '-').replace(/\//g, '_')
            }
        });

    return sendRequest.execute(function(){});
}

Answer 1

Don't change the "userId" in the URL path. Just set the "From" header in your email to that address (and it has to be a verified address for your Gmail account for that to work).