A Masked Email is a unique, throwaway address you hand out instead of your real one. Mail to it lands in your normal inbox — and if it ever starts attracting spam, you switch that one address off without touching your real email.
Create a Masked Email address
Open Masked Email
Click the Settings gear. In the left margin under Set up, click Masked Email.
Make a new one
Click New Masked Email address.
Copy it
Fastmail creates a unique address (like
slow.nail4097@fastmail.com). Click Copy to clipboard.Describe it
In Description, note what it’s for (the website’s name), then click Save.
Use it instead of your real address
Paste the masked address into that website’s sign-up form — not your real one.
You don’t check a separate inbox. Anything sent to a Masked Email address arrives in your normal Fastmail inbox, and when you reply it goes out from the masked address — so the company never learns your real one.
Getting spam at one address? Open Masked Email, find it by its description, and set it to Blocked. The junk stops immediately — and because only that one company had the address, you know exactly who passed it around.
For power users. If you use 1Password or Bitwarden, their browser extensions can create a Masked Email right on a sign-up page. Businesses can also create masked addresses on their own domain.