A forwarding email alias is an address that is not your real address but delivers mail directly to your real inbox. Instead of giving a website your actual Gmail or Outlook address, you give it something like randomstring@simplelogin.io, and every message sent to that alias lands in your real inbox, relayed transparently. At any point you can disable or delete the alias, and mail to that address simply stops, without changing your real account or telling the sender what happened. This is one of the most practical privacy tools available for people who want a permanent-but-shielded address rather than a throwaway inbox. This guide explains how alias services work, reviews the main providers, compares them to disposable email, and tells you which tool to reach for in specific situations.
How Email Aliases Work
When you create an alias through a service like SimpleLogin or Addy.io, you get a new address on one of the service's domains (or your own custom domain if you connect one). That address does not have its own mailbox — it is a forwarding rule. Any message sent to the alias is received by the service's mail infrastructure, stripped of metadata the service chooses to remove, and forwarded to your configured real address. From your real inbox it looks like a normal email, usually with the alias in the To field so you know which alias received it. When you reply from within your inbox, the service intercepts the reply and re-sends it from the alias address, so your real address is never exposed to the sender. This two-way masking makes aliases much more versatile than simple forwarding, where replies would reveal the destination address.
The alias is a permanent, reusable address — unlike a disposable inbox, it does not expire and does not require you to check a separate web interface. Mail lands in your normal inbox, in your normal mail client, with your normal workflow. The alias is a layer between the world and your real address, not a replacement for it. This is the fundamental design difference from temporary email: an alias preserves the ongoing relationship with a service while protecting your identity, whereas a disposable inbox severs the connection entirely when the inbox expires.
SimpleLogin: Open Source and Proton-Integrated
SimpleLogin is an open-source alias service, which means you can inspect its code or even self-host it if you want complete control. It was acquired by Proton (the company behind Proton Mail and Proton VPN) in 2022, and the two services are now integrated: Proton Mail users can manage SimpleLogin aliases directly from the Proton Mail interface. Free accounts get fifteen aliases; paid accounts (or Proton Unlimited subscribers) get unlimited aliases, the ability to use custom domains, and support for multiple recipient addresses per alias.
SimpleLogin's key strengths are its open-source code (auditable for anyone who cares about the technical implementation), its integration with the Proton privacy ecosystem, its support for connecting your own domain (so your aliases live on a domain you control rather than the provider's), and its browser extension that automates alias creation during the sign-up process — click a button in the extension and it creates a new alias and fills the email field without you leaving the form. The main consideration is cost: the free tier is genuinely limited, and the paid tier requires a subscription, though it is bundled if you already pay for Proton Unlimited.
Addy.io (formerly AnonAddy): Flexible and Privacy-Focused
Addy.io offers a similar feature set with a different pricing and structure model. Free accounts get unlimited aliases on the shared domain (username.addy.io), ten aliases on the service's non-personalized domains, and support for up to one custom domain. Paid tiers remove these limits and add more custom domain slots, bandwidth, and recipient addresses. Addy.io is also open source and runs on EU-based infrastructure with a privacy-first approach, making it a popular choice for users who prioritise auditability and jurisdiction. Its web interface is more technical than SimpleLogin's, which is either a strength or a weakness depending on your comfort level. It also offers a bandwidth cap on free accounts (10 MB per month of total forwarded email), which can be limiting if you receive large attachments through aliases.
Addy.io's distinctive feature is its fine-grained control: you can configure each alias to forward, silently discard, or block mail, set reply-from rules, and manage recipients per alias, all from a dashboard or via its API. Developers who want to automate alias creation and management will find the API particularly useful. The service also supports both wildcard aliases (any address at your subdomain automatically works without pre-creation) and UUID aliases (randomly generated per-site addresses), offering flexible patterns for different use cases.
Apple Hide My Email: Frictionless if You Are in the Apple Ecosystem
Apple introduced Hide My Email as part of iCloud+ (the paid iCloud subscription tier). If you pay for any iCloud+ plan (50 GB, 200 GB, or 2 TB of iCloud storage), Hide My Email is included at no extra charge. It generates random apple.com-subdomain addresses (of the form randomstring@privaterelay.appleid.com) and forwards them to your Apple ID email. Creation is integrated into Safari autofill on iOS, iPadOS, and macOS — when a website asks for an email address, Safari offers to generate a Hide My Email alias automatically. You can also create aliases manually through iCloud settings.
The simplicity and friction-free creation are Hide My Email's biggest advantages for iPhone and Mac users: no separate account, no browser extension to install, native OS integration, and included in a storage subscription many people already pay for. The limitations are equally clear: it only works within the Apple ecosystem, you cannot use a custom domain, management is less granular than SimpleLogin or Addy.io, and if you ever leave the Apple ecosystem or let your iCloud+ subscription lapse, the aliases stop forwarding. If you want a service that works regardless of operating system, browser, or future subscription decisions, a dedicated alias service is more durable.
Fastmail Masked Email and Other Provider Options
Some email providers include alias functionality directly. Fastmail, a privacy-focused paid email provider, offers Masked Email — aliases on its domain that forward to your Fastmail inbox, integrated with the Bitwarden password manager so that new account creation auto-generates both an alias and a strong password in one step. Firefox Relay is Mozilla's alias service, offering five free aliases or unlimited with a Premium subscription, with a Firefox extension for frictionless creation during sign-up. DuckDuckGo Email Protection offers @duck.com aliases with the additional feature of stripping email tracking pixels before forwarding the message, making it a combined alias and anti-tracking tool.
Each of these is worth considering in the context of your broader setup: Fastmail Masked Email is most useful if you already use Fastmail and Bitwarden; Firefox Relay if you are a Firefox power user; DuckDuckGo Email Protection if you are already using the Duck browser or extension and want the tracking-strip feature. They all operate on the same alias-forwarding principle.
Alias Services vs Temp Mail: Which to Use When
The key distinction is permanence and relationship. An alias is the right tool when you want ongoing mail from a service but not at your real address: an online shop you buy from regularly, a subscription you want to evaluate properly, a forum or community where people will reply to you over time, a professional contact where you need a stable address but want to hide your primary one. The alias stays active, mail flows in, and you manage it from your real inbox. If the shop starts spamming you, you disable the alias; the shop loses the ability to reach you without you revealing your real address or dealing with their unsubscribe process.
A disposable inbox like TempMailKit is the right tool when you need a one-time gate that should then disappear: a download, a coupon code, a one-off forum registration, a trial where you have no intention of ongoing use. The inbox is gone when the relationship is over, so there is nothing to manage, disable, or worry about being breached later. The practical triage: if you expect to receive more than one email from a service over time, use an alias; if you need exactly one email (a confirmation link, a code), use a disposable inbox. We map this decision out in full in disposable vs burner vs alias.
There is also a cost dimension: all major alias services charge for full functionality, while disposable inboxes are typically free. For users who sign up for dozens of new services regularly, the cost of a paid alias service (usually around $2-4 per month) is modest relative to the privacy benefit. For users who only occasionally need a throwaway address for one-off sign-ups, a free disposable inbox does the job without any ongoing expense.
Setting Up an Alias Service in Practice
The core workflow is simple: install the browser extension of your chosen service (available for Chrome, Firefox, and Safari for most providers), and when you encounter a sign-up form, the extension automatically offers to generate a new alias and fill the email field. Your alias manager stores a record of which alias you used for which site. When you receive an email through an alias, the service's forwarding label in the message tells you which alias caught it, so you always know where a message came from even without checking your alias dashboard. Replies go out from the alias, not your real address.
The management habit that makes aliases powerful over time is review and pruning: when you notice a particular alias is receiving more spam or marketing than mail you care about, disable or delete that alias. The service that was sending through it loses its route to your inbox permanently, without you touching their unsubscribe link, revealing your real address, or worrying about whether their opt-out actually works. This is the most decisive version of inbox control available short of not signing up in the first place.
The Short Version
Email alias services create permanent forwarding addresses that relay to your real inbox while keeping your actual email address hidden. They are the right tool for ongoing relationships with services where you want to remain reachable but maintain the ability to cut contact cleanly. The major providers are SimpleLogin (open-source, Proton-integrated, good free tier), Addy.io (open-source, more granular control, EU-based), Apple Hide My Email (frictionless for Apple users, requires iCloud+ subscription), and Firefox Relay (good for Firefox users, Mozilla-backed). Disposable inboxes like TempMailKit are better for one-time gates where the address can expire after a single confirmation link; aliases are better when you expect ongoing mail. The two tools are complementary rather than competing: use disposable inboxes for throw-away sign-ups and aliases for arm's-length but ongoing relationships, reserving your real address only for services where it genuinely matters.
Frequently Asked Questions
What is an email alias?
An email alias is a forwarding address that routes messages to your real inbox without revealing your real address to the sender. You give the alias to a service; any email sent to it is forwarded to your real account; when you reply, the service intercepts the reply and re-sends it from the alias, maintaining the masking in both directions. The alias is persistent and reusable, unlike a disposable inbox, but you can disable or delete it at any time to cut off a specific sender.
Is SimpleLogin free?
SimpleLogin offers a free tier with fifteen aliases, which is enough for light use and to evaluate the service. Paid plans (or inclusion in Proton Unlimited subscription) unlock unlimited aliases, custom domains, and multiple recipients per alias. For users who already pay for Proton Unlimited for its email and VPN services, SimpleLogin's full feature set is included at no additional cost.
How is an alias different from a disposable email address?
An alias is permanent, forwards to your real inbox, and is designed for ongoing use. A disposable email address has its own short-lived inbox, expires automatically, and is designed for one-time use. Use an alias when you need ongoing mail from a service; use a disposable inbox when you need a single confirmation and then want the address to disappear. The two serve different parts of the privacy-management problem.
Can I reply from an alias address?
Yes, with all major alias services (SimpleLogin, Addy.io, Fastmail Masked Email, Firefox Relay). When you reply to a forwarded message from within your real inbox, the service intercepts the outgoing reply and re-sends it from the alias, so your real address is never exposed. The sender sees a reply from the alias address and never learns your actual email. This two-way masking is what distinguishes a full alias service from simple email forwarding.
What happens to emails if I delete an alias?
They stop being delivered. Mail sent to the deleted alias arrives at the alias service's servers, has no forwarding rule to follow, and is discarded (or bounced with a delivery failure, depending on the service's handling). Your real inbox is unaffected because the alias, not your real address, is what the sender has. This is the clean break that makes aliases a powerful inbox management tool: deleting the alias severs the connection permanently without revealing your real address or relying on the sender to honour an unsubscribe request.
Achyuth Kumar
Founder & editor, TempMailKit
Achyuth builds privacy tools and writes TempMailKit’s guides on email security, spam, and online privacy. Every article is checked against primary sources and our editorial policy before it is published. Questions or a correction? Get in touch.