Masked Email is Fastmail's alias feature, and the quickest way to understand it is to look at what it is attached to. Fastmail is a mail host. It runs the mailbox, stores the messages, indexes them for search and serves them to your phone and your laptop. Masked Email adds disposable addresses to a mailbox Fastmail already operates for you. Alias services work the other way round. They hand you addresses that forward into a mailbox somebody else runs.
We make YeyMail, which is a forwarder, so read this knowing we sell the other shape. We have tried to make this the fairest page about Masked Email anywhere, and where Fastmail is plainly better we say so rather than hedging. The hosting versus forwarding split is not a feature you can settle in one row of a comparison table. It is a different product, and it decides who should buy which.
Every fact below was checked against fastmail.com, fastmail.help and 1Password's support site on the day this was published. Fastmail prices in local currency and shows tax inclusive figures, so the numbers quoted here are the euro ones we were served. Where their pages do not answer a question, we say that instead of guessing.
What Masked Email actually is
Inside the Fastmail app you go to Settings, then Masked Email, then click New Masked Email address. Fastmail generates the address for you rather than letting you invent one. Their help page describes the format as random words plus a random number, giving dog.food3495@domain.tld as the example. Each address can carry a description so you remember which service it belongs to.
Fastmail does not publish a number, but there is more than a rate limit. Their account limits page says they have limits on users' total number of Masked Email addresses, as well as how many new Masked Email addresses can be created within a certain amount of time to prevent abuse, and the Masked Email help page repeats the creation limit with the advice to try again in 24 hours. So there is both a ceiling and a rate limit, and neither is numbered. For normal use, signing up to a handful of sites a week, neither is likely to come up, but do not read the missing number as unlimited.
The real price of Masked Email is the mailbox price
This is the part people miss when they compare Masked Email to a forwarder on price. Masked Email is not sold separately. You cannot buy it without buying a Fastmail mailbox, and Fastmail has no free tier at all, only a trial. So the price of the alias feature is the price of hosting your mail.
| Plan | Monthly | Yearly | Masked Email | Custom domains |
|---|---|---|---|---|
| Individual | €6 | €5/mo (€60) | Yes | Yes |
| Duo | €10 | €8/mo (€96) | Yes | Yes |
| Family | €14 | €11/mo (€132) | Yes | Yes |
| Business Basic | €4/user | €3/user (€36) | Yes | Not supported |
| Business Standard | €6/user | €5/user (€60) | Yes | Yes |
| Business Professional | €10/user | €9/user (€108) | Yes | Yes |
Masked Email is ticked on every plan in the comparison table, Business Basic included. What Basic does not get is custom domains, so masked addresses on that plan can only be at fastmail.com. Their custom domain help page puts that rule in words: at least one admin of the account must be on a non-Basic subscription plan. New accounts get a trial, described on the pricing page as free for up to 30 days, and the trial accounts help page says no credit card is required to sign up. That page also lists the trial's restrictions, including a maximum of five email addresses and a cap of 120 messages sent a day, and states that trial accounts lose the ability to send and receive mail if they are not paid for at the end.
The 1Password integration is the best thing about it
Credit where it is due. Masked Email in 1Password is the smoothest alias flow anyone ships. You connect the accounts once, from 1Password.com, by choosing Integrations then Fastmail in the sidebar and following the prompts. After that, when you hit a signup form, you select the email field in the 1Password browser extension, choose Create Masked Email, then Fill Email. The address is generated and filled without leaving the page, and it lands in the same vault item as the password you just made.
Under the hood this is a JMAP extension that Fastmail documents publicly, including a forDomain property that password managers set to the origin of the site the address is for. Bitwarden connects too, through its Generator, though Fastmail notes that connecting to Bitwarden must be done via API token. One asymmetry worth knowing: creation happens in the password manager, but deletion does not. 1Password's page sends you back to Fastmail, Settings, Masked Email, to delete an address. If you like this pattern, we wrote more about it in aliases and password managers.
Creating, blocking and replying
Fastmail's help page gives each masked address three states, and the difference between the last two matters:
- Active: the address is currently able to receive mail.
- Blocked: any messages sent to the address will go to your Trash folder.
- Deleted: any messages sent to the address will bounce.
Blocking is soft. The sender still gets a delivery, it just arrives in Trash, so a leaked address that you block quietly keeps accepting mail on your behalf. Deleting is the hard stop that pushes the failure back to the sender. Both options being present is good design, as long as you know which one you clicked.
Replying is where hosting wins outright, and we will not pretend otherwise. Because Fastmail is your mail server, a reply to a message that arrived at a masked address goes out from that masked address by default, and you can start a new conversation from one by opening the compose dropdown and choosing Show all. There is no reply-all footnote, no second SMTP setup, no daily reply quota. With a forwarder, including ours, replies to the original sender are rewritten for you, but reply-all is the documented exception: the other people on the thread are ordinary addresses in your mail app, so those replies go out from your real account. Fastmail simply does not have that problem, because nothing is being rewritten.
Your own domain, and why it matters more here
Masked addresses can be created at fastmail.com or at a custom domain that has been set up in your Fastmail account. Fastmail is a full mail host for that domain, so this is not forwarding with extra steps, it is your domain's mail actually living there. Their custom domain page also notes that registering a domain through Fastmail is available to paid customers.
There is a trap attached. Fastmail states that if the custom domain used to create Masked Email addresses is removed from your account, the masked addresses at that domain are also deleted from the account, and messages sent to them will bounce. Removing the domain from Fastmail and pointing it somewhere else does not carry your masked addresses with it, so plan any move address by address. The domain is still the thing that makes leaving possible, which is the same argument we make for aliases on a domain you own.
What a lapse costs, and it costs more here
For a forwarder, a lapsed subscription is an inconvenience. For a host, it is your archive. Fastmail's expired subscriptions page describes a slow slide rather than a cliff: a reminder two weeks before the subscription ends, another once it has expired, then roughly weekly reminders, then sending and receiving disabled, then, if the account is still not renewed after a few weeks, access disabled, and eventually the entire account deleted including all stored messages. The page does not attach day counts to those later stages, so we will not invent any.
Deliberate cancellation is documented more precisely. You keep the account for the rest of the current billing cycle, it closes on the expiration date, mail sent to your Fastmail addresses is then rejected, and all data is permanently deleted after 7 days, with support able to reactivate before that. Fastmail also states that once an account has been deleted, the username and any addresses on it can be re-used, which is a real consideration for addresses you handed to a bank. We wrote about the general version of this problem in what happens if you stop paying.
Stored with them, or discarded in transit
Here is the trade in one line. Hosting means your mail is stored with Fastmail, which is precisely why it is useful: it is searchable, it syncs, it is one archive with your aliases inside it rather than an alias layer bolted to the front of somebody else's inbox. Most people want that. It is the normal way to have email.
Forwarding makes the opposite bet. A forwarder passes the message through and, in our case, discards the body once delivery succeeds, keeping metadata for 30 days and activity for 90. Your archive stays where it already is. That is a smaller footprint at the alias layer, but be honest about where it leaves the mail: it lands in the mailbox you already have, which for most people is Google's. If your goal is that no large provider holds your correspondence, a forwarder in front of Gmail does not achieve it, and moving to a host like Fastmail does.
Masked email or alias, as vocabulary
The two words describe the same mechanism. Fastmail says masked, Apple says hide, others say alias or relay, and all of them mean an address that belongs to you and points at your real one. The naming mostly tracks marketing rather than technology, and we untangle the terms in email masking explained. Do not read anything into the label when comparing products.
Who should just use Fastmail
If you already pay Fastmail, stop reading comparisons. Masked Email is included on your plan, it is well built, the 1Password flow is excellent, and adding a separate forwarding service on top would give you two alias systems to remember and no new capability. This is a straight yes.
If you want to leave Gmail entirely, it is also a yes, and for the right reason. Buy the mailbox because you want your mail hosted somewhere that sells email rather than advertising, and treat Masked Email as a good feature that comes with it. Alias services cannot offer you that, because they do not host anything.
The case against is narrow but common. If your mailbox is fine, if migrating years of mail and retraining your household is not a project you want, or if you simply want a disposable address layer in front of the inbox you already read, then paying mailbox prices for an alias feature is the wrong shape of purchase. That is the gap forwarders fill, and we survey the options in the best email alias services.