Receiving always works. Sending from an alias is a separate feature, and not every service has it. Mail sent to an alias is forwarded to you normally — that's the whole point. But when you hit reply, the response comes from your real address unless the service specifically implements reply handling. DuckDuckGo, Apple, Proton Pass, Firefox Relay Premium and SimpleLogin Premium all do. Don't SPAM Me does not, yet.
Why sending is harder than receiving
Receiving is a routing problem: mail arrives for shop@yourdomain.com, the server rewrites the recipient and passes it to your inbox. Simple.
Sending is an identity problem. Your mail client is authenticated as you and will stamp your real address on anything it sends. For the recipient to see the alias instead, the message has to leave through the alias service's infrastructure — which means the service needs a way for you to route outbound mail through it.
The usual mechanism is a reverse alias: the service gives each of your correspondents a unique address on its side. You reply to that instead of to the person directly, the service rewrites the sender to your alias, and forwards it on. It works well, but it's real machinery, which is why it's typically a paid feature.
Who supports it
| Service | Reply from alias |
|---|---|
| DuckDuckGo Email Protection | ✓ Free |
| Apple Hide My Email | ✓ In Mail, with iCloud+ |
| Proton Pass | ✓ Including the free tier |
| Firefox Relay | ✓ Premium only |
| SimpleLogin | ✓ Premium (reverse-alias) |
| Don't SPAM Me | ✗ Not yet — forwarding is one-way |
| Plus-addressing (Gmail etc.) | Partially — you can set it as a send-as identity, but it exposes your real address anyway |
What happens if you reply without it
Your real address is revealed to the recipient. Nothing breaks, no error appears — the message simply arrives from you@gmail.com instead of the alias, and the company now has the address you were avoiding giving them.
It's a quiet failure, which is what makes it worth knowing about in advance. If your service doesn't support replying and you need to respond, the safe options are to use the company's web form or in-app messaging, or to reply from a different alias you've already given them.
Does it matter for your use case?
Honestly, for a lot of people it doesn't. The bulk of alias mail is one-way: receipts, dispatch notices, newsletters, verification codes, account notifications. None of that wants a reply.
Where it does matter:
- Customer support threads. Common, and the most likely reason you'll hit this.
- Marketplace selling. Buyer questions arrive by email and need answering.
- Anything approaching correspondence — a landlord, a tradesperson, a small supplier.
If those describe you, treat reply support as a requirement and pick accordingly. It's a genuine reason to choose SimpleLogin, Proton Pass or DuckDuckGo over us — we say so on each of those pages.
What replying reveals anyway
The recipient sees your alias, not your inbox. They still see your name if it's in your display name, your signature if you have one, and anything you write. Reply support hides the address, not the correspondence.