GSuite support was surprisingly helpful and prompt after emailing them.
Note: Please read the important extra details at the bottom of my answer.
You can achieve that in two ways, depending on what you prefer.
First option: (Create a new user and a new organizational unit and set up a routing rule that rejects all incoming messages for that
- Create a new user (in this case “firstname.lastname@example.org”) > Create a new organizational unit
(https://support.google.com/a/answer/182537?hl=en) > Move the new user
to the new organizational unit
- After that, go to Apps>G Suite>Gmail>Advanced settings.
- On the left, select the new organization.
- Scroll to the Routing setting in the Routing section, hover over the setting, and click Configure.
- Make sure to enter a description for the rule at the top
- Under "Messages to affect" select Inbound and Internal receiving
- Under “For the above types of messages, do the following”, select “Reject message”
- Optional: Add a rejection message
- Click Save
- Click Save again in the bottom right of the screen.
Fore more information on routing, please visit
Second option: (Create an email alias and set up a filter that automatically delete every incoming email to that alias)
- Create an email alias for one of the user (https://support.google.com/a/answer/33327?hl=en)
- Create a filter with search criteria as follow: To: email alias address
-Click on “Create filter” and tick “Skip the Inbox”, “Mark as read”, “Delete it”
For more information about filters, please visit
If you can create a new user, I would recommend the first option,
because the inbound messages will never reach the inbox and the sender
will get a rejection message.
Some points of note:
For Option 1 you will incur extra monthly fees for adding an extra user unless you have available ones under your current plan.
Additionally, at least for my situation, I have decided it best that Option 2 would probably be the better option as with Option 1 it seems to act the same as if the mailbox doesn't exist, which is exactly the problem I am trying to avoid.
So to summarise:
- Option 1 may incur extra fees and will act as if the mailbox doesn't exist as the user will be returned a rejection message.
- Option 2 will not cost any extra and will "fail" silently.