alias.mom
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How it works Why the address looks like that We check the reply is really from you Common refusals, in plain terms Writing first

Replying

Someone writes to your alias. You hit reply. It should work, and your real address should not appear anywhere.

How it works

The first time a sender writes to one of your aliases, we mint a masked reply address for that specific pairing and put it in Reply-To. Replying goes to that address, we recognise it, and we send the message on to the real recipient with your alias as the sender.

They see your alias. They never see your mailbox.

Why the address looks like that

Something along the lines of re.a8f21c4b@alias.mom. Not beautiful. Every service that does this produces something similar, for the same reason: the address has to encode which alias and which contact without being guessable, because anyone who guesses one can send mail that appears to come from you.

The random part is signed rather than sequential, so incrementing it gets you nothing.

We check the reply is really from you

A reply is only accepted from a mailbox that belongs to the alias. Otherwise anyone who saw one of these addresses in a header could impersonate you to your own contact, which is worse than useless.

If you send from a different address, add it under authorised addresses in settings. Common cases: a work account, a phone that sends from a different identity than you expected, an alias of your own on another service.

Common refusals, in plain terms

  • "Not authorised to send from this alias": the address you sent from is not a verified mailbox for it. Add it in settings.
  • "This alias has no mailbox": it is inbox only, so there is nothing to authenticate against. Reply from the web inbox instead.
  • "Alias disabled": exactly what it says. Turn it back on.

Every refusal is a real sentence rather than a code, because these end up quoted verbatim in a bounce message that lands in your inbox, and the person reading it should be able to fix it.

Writing first

You can also start a conversation from an alias, to someone who has never written to you. See reverse aliases for the details, and note the same rule applies: the alias needs a mailbox, or use the web inbox.

Something here wrong or missing? Tell us. These pages live in the same repository as the code, so a correction is a one-line change.