Gmail – Why Emails to Disabled Accounts Don’t Bounce

I worked it out.

In the original email that Gmail sent out to the external address in order to "verify" it there was the following section:

If you accidentally clicked the link, but you do not want to allow xxx@yyy.com to send messages using your address, click this link to cancel this verification: https://mail.google.com/mail/blahblahblahblahblah

I found it just by grepping his maildir, clicked the link and it said he can no longer send using his work address.

I realise you can just spoof the "from" headers willy-nilly, but you have to be technically savvy enough to know that this is possible and 99% of my users are not, including this one.

MX records control only the server direction (i.e. messages sent to @example.com will be handled by the server located at 123.123.123.123). It's the local mail server that decides that admin@example.com and mail@example.com correspond to the same inbox. Google uses the term nickname for forwarded addresses.

In order to create a nickname for an existing user/inbox in Google Apps, you need to do the following:

1. Go to your Google Apps admin dashboard
2. Click on Organization and users in the blue navigation menu on top of the page
3. Click on the user, to which you want to assign a nickname
4. In the User information tab (the default one) click on Add a nickname (it's right below Email quota)