Choose Firefox Relay if you mainly want quick, browser-integrated masks for shopping, apps and other low-stakes sign-ups; Mozilla currently documents up to 50 free masks. Choose SimpleLogin if you need open-source software, several mailboxes, catch-all handling, multiple custom domains or the ability to start a new message from an alias. SimpleLogin’s listed free allowance is 10 aliases, while Firefox Relay Premium removes the mask limit but Mozilla’s reviewed help pages do not state a current subscription price.
Neither service is appropriate for every account. Mozilla specifically advises against masks when a bank, doctor, lawyer, airline or other service must verify your identity or send important attachments. Treat the comparison below as a workflow and feature decision, not a security, anonymity or deliverability ranking.
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What an email alias does
An email alias is an alternate address that forwards incoming mail to your real inbox. You give the alias to a website, store or app instead of exposing your primary address. The service keeps the forwarding relationship in its dashboard, so you can disable or delete an address without changing your main mailbox.
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Both SimpleLogin and Firefox Relay follow that basic model. A message sent to an alias is relayed to the destination mailbox you configured. The practical differences are how many aliases you can create, how you create them, whether you can send new messages from them, and how much control you get over domains and mailboxes.
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An alias is not a guarantee that a sender cannot identify you. Messages still pass through a forwarding service, and a website can reject an alias or require another form of verification. Use one for separation and address control rather than promising complete anonymity.
Which service fits your situation?
| If your priority is… | Better starting point | Reason |
|---|---|---|
| Browser-integrated suggestions and the larger documented free allowance | Firefox Relay | Mozilla describes creating masks from email fields in Firefox and allows up to 50 free masks. |
| Open-source software and a broader alias-management setup | SimpleLogin | SimpleLogin describes its relay as open source and lists browser extensions plus iOS and Android apps. |
| More than one custom domain, catch-all routing or several mailboxes | SimpleLogin Premium | Its listed Premium features include unlimited custom domains, catch-all and unlimited mailboxes. |
| Creating an address spontaneously while away from a computer | Firefox Relay may fit | With a custom Relay domain, sending mail to a chosen username at that domain can create a mask that appears in your dashboard. |
| Starting a brand-new outbound message from an alias | SimpleLogin Premium | SimpleLogin lists alias-initiated email as a Premium feature. |
| Blocking promotional messages while retaining selected mail | Firefox Relay Premium | Mozilla documents promotional-email blocking for Premium accounts. |
The word “better” therefore depends on the job. Relay is the simpler first stop for Firefox users who want many free masks. SimpleLogin is the more capable choice when aliases are part of a structured mail setup rather than occasional disposable addresses.
Free limits and paid plans
The figures below are provider-published plan details. They can change, so confirm the live plan page before paying. The comparison reflects the plans documented in October 2026.
| Plan or feature | SimpleLogin | Firefox Relay |
|---|---|---|
| Free alias or mask allowance | 10 aliases | Up to 50 masks, according to Mozilla’s current help documentation |
| Paid alias or mask allowance | Unlimited aliases on Premium | Unlimited masks on Premium |
| Published paid price | $36 per year or $4 billed monthly on the listed pricing page | Not stated on the reviewed Mozilla help pages |
| Reply to forwarded mail | Listed on the free plan | Premium feature |
| Start a new message from an alias | Premium feature | Not established by the reviewed help pages |
| Custom domains | Unlimited on Premium | One unique Relay domain per Premium account |
| Catch-all routing | Premium feature | Not established |
| Mailboxes | One on free; unlimited on Premium | Not established |
| Promotional-email blocking | Not established | Premium feature |
SimpleLogin Free
SimpleLogin lists a $0 plan with 10 aliases, unlimited bandwidth, reply from an alias, one mailbox, browser extensions, iOS and Android apps, and TOTP and/or WebAuthn support. That combination is useful if you need only a small number of persistent addresses but still want to answer a sender without revealing the mailbox address.
SimpleLogin Premium
The listed Premium price is $36 per year or $4 when billed monthly. Features include unlimited aliases, unlimited custom domains, catch-all routing, five subdomains, 50 directories or usernames, unlimited mailboxes, PGP encryption and the ability to initiate a new email from an alias. The plan page also says Proton Pass premium features are included. Because the page does not state a publication date, regard the price and feature bundle as a snapshot rather than a permanent promise.
Firefox Relay Free
Mozilla’s help documentation currently says a free account can create up to 50 masks. That is five times SimpleLogin’s documented free allowance, making Relay attractive for someone who wants a separate address for many stores, newsletters and applications without subscribing.
Rank #2
Firefox Relay Premium
Mozilla says Premium removes the mask limit and adds replies to forwarded messages, promotional-email blocking and registration of a custom Relay domain. The reviewed Mozilla pages describe these features but do not establish a current subscription price, so check the purchase screen for your country before treating Premium as a budget comparison.
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How custom domains differ
SimpleLogin: several domains and catch-all control
SimpleLogin Premium lists unlimited custom domains. It also lists catch-all routing, which can let addresses under a domain be handled without creating each alias manually. Five subdomains and 50 directories or usernames are included in the listed Premium feature set. This is the stronger fit if you own multiple domains, want a branded address structure or expect to create aliases at scale.
Using a personal domain also gives you continuity if you later change forwarding providers: the domain remains yours, although the DNS and routing configuration must be moved correctly. The provider’s plan description supports the availability of custom domains and automated alias creation; it does not establish guaranteed acceptance by every recipient website.
Firefox Relay: one shared Relay domain
Firefox Relay Premium allows one unique Relay email domain per account. Mozilla says the domain uses the shared mozmail.com service and cannot be changed once selected. You choose a username before that domain; when a message is sent to the address, the mask can appear in your Relay dashboard.
This approach is convenient for creating an address on demand, but it is not the same as bringing several domains that you own. Mozilla also notes that some websites may reject addresses using a Relay subdomain or accept only well-known providers. If a checkout form refuses the address, try another alias only if the site permits it; do not assume the rejection means mail forwarding has failed.
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Replying to a forwarded message
Replying is the common workflow: a message arrives through the alias, and you press Reply in your ordinary mailbox. SimpleLogin lists reply-from-alias on its free plan. Firefox Relay documents replying to forwarded email as a Premium feature. In both cases, the service is intended to preserve the alias as the visible sender rather than exposing your real mailbox address.
Before relying on a reply for an important conversation, send a test to a second address and inspect both the From and Reply-To fields. A forwarding rule can deliver the incoming message correctly while a recipient-side system still treats the reply differently.
Starting a new outbound message
There is a meaningful difference between replying and initiating. A reply already has an incoming thread for the service to associate with an alias. A new message requires you to select an alias as the sender without an existing forwarded conversation.
SimpleLogin lists initiating a new email from an alias as a Premium capability. The reviewed Firefox Relay pages establish replies for Premium but do not establish an equivalent general-purpose “compose from any alias” feature. If you routinely contact a person or service first, that distinction should push your choice toward SimpleLogin Premium.
Browser, phone and everyday workflow
Firefox Relay in Firefox
Mozilla describes mask creation directly from email fields in Firefox. That makes Relay useful when you are registering for a site and do not want to open a separate alias dashboard: create or select a mask at the form, submit it, and let Relay forward messages to your real address. Mozilla’s support instructions are at Create an email mask through Firefox Relay.
This convenience is the main reason to choose Relay even when SimpleLogin offers more administrative controls. The browser-integrated flow reduces friction for one-off sign-ups, and the 50-mask free allowance leaves room for many independent addresses before a subscription is necessary.
SimpleLogin across browsers and phones
SimpleLogin lists browser extensions and iOS and Android apps on its free plan. That points to a more service-oriented workflow: create aliases from the extension or app, assign them to a mailbox, and manage the list centrally. The open-source positioning may also matter to readers who want to inspect or self-host software, although the feature list alone is not a security audit.
Rank #4
If you use several browsers, phones or mailboxes, the central-management model can be more important than the number of free aliases. Decide whether you want a quick mask at a web form or a durable address inventory that you can organize by domain, mailbox and purpose.
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Important accounts and identity checks
Mozilla recommends masks for less critical sign-ups such as shopping, apps and sites you do not fully trust. It says: “We don’t recommend using masks when you need your identity verified or for very important emails or those where you must receive attachments.” The guidance appears in Mozilla Support’s page updated April 21, 2026: Create an email mask through Firefox Relay.
Mozilla’s examples include a bank, doctor, lawyer and concert or flight boarding pass. Those services may need a stable identity, may send time-sensitive attachments or may block forwarding addresses. Applying the same caution to any alias provider is sensible editorial practice, but the quoted warning is specifically Mozilla’s guidance for Relay.
- Use your primary address, or an address the institution explicitly accepts, for banking, medical, legal and travel accounts.
- Do not use an alias for a verification process if losing access would lock you out of the account.
- Keep a record of which address you used for recovery and security notifications.
- Test delivery before relying on an alias for a deadline-sensitive event.
What happens if you cancel SimpleLogin Premium?
SimpleLogin says aliases and domains already created continue to work after a subscription ends. If you are above the free alias limit, however, you cannot create new aliases, add domains or add mailboxes until you return within the free allowance or resubscribe. This makes cancellation less disruptive than an immediate shutdown, but it does not preserve Premium growth and management capabilities indefinitely.
Export or document your alias inventory before cancelling. Note the address, purpose, destination mailbox and any account-recovery role. A forwarding service can continue to deliver existing mail while you still lose the ability to expand the setup, which is easy to overlook when planning a downgrade.
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You need a few addresses for shopping and newsletters
Start with Firefox Relay Free. Its documented 50-mask allowance is generous for occasional sign-ups, and Firefox can suggest a mask directly in an email field. Use a separate mask per store or newsletter so that you can identify and disable one address without affecting the rest.
You want the largest free allowance
Relay currently has the larger documented allowance: up to 50 free masks versus SimpleLogin’s 10 free aliases. That is a capacity comparison only; it does not establish that one service forwards mail more reliably or protects privacy better.
You own several domains or need catch-all routing
Choose SimpleLogin Premium as the more suitable starting point because its listed features include unlimited custom domains and catch-all. Relay’s one-domain limit is designed for a simpler shared-domain workflow, not a multi-domain mail architecture.
You manage family, team or project mailboxes
SimpleLogin is the clearer fit when several destinations matter: its Premium plan lists unlimited mailboxes, compared with one mailbox on the free plan. Create a routing scheme before adding aliases so personal, household and project messages do not become an unlabelled stream.
You need to send the first message from an alias
SimpleLogin Premium is the documented choice because it lists alias-initiated email. Relay’s reviewed documentation confirms replies to forwarded messages for Premium but does not establish a comparable new-message workflow.
You want to suppress marketing mail selectively
Firefox Relay Premium may fit because Mozilla lists promotional-email blocking. Check how the control behaves for your account before enabling it broadly; blocking should be applied to promotional traffic, not to receipts, account alerts or recovery messages you still need.
Setup checklist before using an alias
- Define the account’s importance. If it involves identity checks, regulated services, medical or legal records, financial access or irreplaceable travel documents, use an address the provider explicitly accepts instead of an alias.
- Choose a naming scheme. Use a purpose-based label such as a store, service or project name so you can recognize the sender without opening the message.
- Create the alias or mask. In Firefox, use Relay’s email-field integration; with SimpleLogin, use its extension, app or account interface.
- Confirm forwarding. Register with the new address and wait for the confirmation message. If no mail arrives, check the service dashboard, destination mailbox filters and the sender’s spelling.
- Test a reply when needed. Reply to the first message and verify that the recipient sees the alias rather than your real mailbox address.
- Record recovery details. Store the alias alongside the account’s recovery method. Do not make an alias the only recovery route until you have proved that it remains accessible.
- Disable selectively. If one address attracts unwanted mail, turn off that alias instead of abandoning every alias tied to the mailbox.
Troubleshooting common failures
A website rejects the address
Some websites reject Relay subdomains or allow only addresses from providers they recognize. Try the site’s documented alternative, such as a different contact address, rather than repeatedly submitting the same rejected alias. A rejection does not prove that forwarding is broken.
The confirmation email never arrives
- Check that the alias was copied correctly and is active.
- Look in spam, junk and filtered folders in the destination mailbox.
- Verify that the forwarding mailbox has not reached a storage or policy limit.
- Send a test message from another account to separate a sender-side delay from a routing problem.
You can receive mail but cannot answer
Confirm which plan includes replies. SimpleLogin lists replies on Free, while Firefox Relay lists replying to forwarded messages for Premium. Also inspect the message’s Reply and From fields; a normal mailbox reply is not proof that the alias will be preserved.
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Check whether your existing aliases exceed the free allowance of 10. SimpleLogin says existing aliases and domains continue working after cancellation, but creation of new aliases, domains and mailboxes is restricted when you are over the free limit.
Limits of this comparison
The documented figures are plan facts, not independent performance measurements. The available pages do not establish comparative deliverability, uptime, spam rates, anonymity guarantees or a categorical security winner. Prices, limits and included features can change, and Relay’s subscription price was not stated on the reviewed Mozilla help pages. Recheck each provider’s current plan and domain documentation before subscribing or moving an important account.
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