In short. An email alias is a separate address that forwards mail to your main inbox. It hides your main address from the website you give it to, but not from whoever forwards the mail.
How an alias works
Mail sent to an alias goes to the alias’s server, which swaps the alias for your real address and passes the message on to your inbox [1]. You read it where you read the rest of your email.
- Replies. Some alias services let you reply from the alias too, so your main address stays hidden in the conversation. Others forward only: if you reply from your inbox, the other side gets your main address.
- Turning it off. If an alias starts getting spam, you turn it off, and mail sent to it stops reaching you. Your main address doesn’t change.
Alias, main address, temporary email
| Alias | Main address | Temporary email | |
|---|---|---|---|
| What it is | a separate address that forwards to your inbox | the address you actually use | a throwaway inbox for minutes or hours |
| How long it lasts | until you turn it off | for years | minutes or hours |
| Hides your main address | from websites, yes | no | yes, but you can’t get mail at it later |
| Who sees your mail | the alias service, then your email provider | your email provider | often anyone who knows the address |
More on choosing between them: Temporary email, alias or private inbox?
When an alias helps
- Signing up on websites and in shops. Each one gets its own alias, and your main address stays out of their databases.
- Newsletters. When you no longer want one, turn its alias off.
- Finding out who passed your address on. If spam arrives at an alias you gave to only one shop, you know where it came from.
Where it stops
- The alias service sees every email it forwards. It is the one swapping addresses, so your mail passes through it.
- An alias shows its domain. On the service’s domain, the website you give it to and anyone you write to from it can tell which alias service you use. On your own domain, the address doesn’t name the service, but your domain’s public DNS records do, and every alias on that domain can be linked to the others.
- A plus address isn’t an alias. An address like name+shop@provider is a tag on your own mailbox [2]: anyone can drop the part after the plus and get your main address.
- An alias doesn’t make you anonymous. Your email provider, your payment details and your IP address can still identify you: what actually gives a person away in email.
Aliases in Methmail
After launch, you’ll be able to create aliases: separate addresses for signing up on websites. Email to an alias will arrive in your mailbox, and you’ll be able to turn an alias off in one step. An alias hides your main address from the website, but not from us: we’ll know whose alias it is, otherwise we couldn’t deliver the email.
Questions
Is an alias the same as a second email address? No. An alias has no inbox of its own: mail sent to it lands in your main inbox. A second address with its own account has its own inbox and password.
What’s the difference between an alias and forwarding? An alias is an address made to pass mail on [1]. Forwarding is a setting that sends mail from one inbox to another, and both inboxes keep existing.
What is a masked email? Another name for an alias that hides your main address: a separate address, often random, that forwards to your inbox.
What’s next
Sources
- RFC 5321: Simple Mail Transfer Protocol, section 3.9.1, Alias. IETF, October 2008: “the recipient mailer simply replaces the pseudo-mailbox address in the envelope with each of the expanded addresses”. https://www.rfc-editor.org/rfc/rfc5321
- RFC 5233: Sieve Email Filtering: Subaddress Extension. IETF, January 2008. https://www.rfc-editor.org/rfc/rfc5233