How they work
You open the website of a temporary-mail service and an inbox is already there, under a random name. You use that address to sign up somewhere, read the confirmation email in the browser, and close the tab. Some of these inboxes last ten minutes, some a day, and some are open for anyone to read. Nobody ever comes back to them.
Why people use them
- To get a download, a discount code or a free trial without getting marketing mail afterward.
- To sign up again and again for something that is free once per person.
- To try a product without giving anything away.
- To test their own software.
Most of these people are not being hostile. They are telling you they do not want to hear from you yet.
Why they matter to a sender
- The address stops working. Later mail bounces or goes nowhere, and bounces count against you. See why emails bounce.
- Your numbers are wrong. A list of 10,000 sign-ups with 1,500 throwaway addresses is a list of 8,500.
- You cannot reach the customer. No password reset, no invoice, no warning that a trial is ending.
- Free offers get used many times by the same person.
How they are detected
By the part after the @. Temporary-mail services run on domains of their own, and those domains are known. BounceTest recognizes more than 9,000 of them, and an address at one is marked Disposable on sight, without asking any mail server.
Asking the server would not help anyway: at the moment you check, the mailbox really does accept mail. The problem is that it will not tomorrow.
New services and new domains appear all the time, so a list like this is never finished and has to be kept up to date. A brand-new throwaway domain can slip through for a while.
What is not a disposable address
A few kinds of address look unusual and are perfectly good:
- Forwarding aliases from services such as Apple's Hide My Email, Firefox Relay or DuckDuckGo. They pass mail on to a real inbox for as long as the person wants.
- Plus addresses like
anna+shop@gmail.com. That is Anna's ordinary mailbox with a label. - Free mailboxes at Gmail, Outlook or Yahoo. Free is not temporary.
- Role addresses like
info@orsales@. A real inbox, read by several people.
Treat these as you would any other address.
What to do with them
- On a list you already have: remove them before you send. They will never read anything.
- At sign-up: either ask for another address, or accept it and note it, depending on how much a real contact matters to you. For a paid trial it matters a great deal; for a newsletter, less.
Removing throwaway addresses is one step in cleaning an email list.