Off

Mail sent to the alias is refused at our end and the sender gets a bounce. Nothing is stored and nothing is delivered. Turn it back on and forwarding resumes.

This is the reversible one, and it is what you want in almost every case, including the case where an address has started attracting junk.

Deleted

The alias stops working and the address stays reserved to your account. Nobody else can create it, ever.

Use this when you are finished with an address and want to be sure it cannot come back to life in somebody else's hands.

Forgotten

The address is released completely. It is no longer yours, it disappears from your dashboard, and anybody can create it later.

This is the only one with a sharp edge. If a shop still has that address on file and somebody else creates it afterwards, their mail goes to that person. Use it when you want no trace of the address here, and not as a tidier way of deleting.

What happens to mail already in flight

Nothing that arrived while an alias was off is recoverable. We do not keep a copy to release later, because a copy of your mail sitting here waiting is exactly the thing this service exists to avoid.