Email Monster vs Firefox Relay: features, pricing, limits
Last reviewed: 25 September 2026
Firefox Relay wins if you want to reply from an alias and stay inside Mozilla's open source ecosystem. Email Monster wins if you want a bigger free tier, readable custom names, and a newsletter digest. Relay's free plan caps out at 5 aliases, which is the main thing to watch for.
An email mask, or alias, is a disposable forwarding address that hides your real inbox from a given sender. Firefox Relay is Mozilla's version, built into the Firefox browser and extension, while Email Monster works the same way from any browser using addresses on your own personal subdomain.
Feature comparison
| Criteria | Email Monster | Firefox Relay |
|---|---|---|
| Price (paid) | $6.99/year or $2.99/month | Around $1.99/month, current figure not reconfirmed |
| Free tier | Yes, 40 forwarded emails a month | Yes, 5 email masks |
| Alias limit | Unlimited, made up on first use | 5 on the free plan, unlimited on paid |
| Custom domain | No, personal subdomain only | No, a shared mozmail.com subdomain instead |
| Reply from alias | No | Yes, on paid plans |
| Sender blocking | Yes, per alias | Yes, disable a mask |
| Newsletter digest | Yes, weekly or daily | No |
| Browser extension | No | Yes, included on every plan |
| Open source | No | Yes, on GitHub |
| Jurisdiction | Not published | Mozilla Corporation, United States |
| Best for | Unlimited free aliases plus digests | Reply from alias inside Firefox |
Facts verified on 25 September 2026 against Firefox Relay's public pricing page.
Where Firefox Relay wins
Firefox Relay is open source, with its code published on GitHub, and it supports replying from a mask on paid plans, which Email Monster does not offer. Its extension is included at every tier, including free, and Mozilla has a long track record on privacy.
Where Email Monster wins
Email Monster's free plan is not capped at 5 aliases; it allows unlimited aliases with 40 forwarded emails a month included. You also choose readable names like amazon@yourname.eml.monster instead of a random mozmail.com string, and Premium adds a newsletter digest Relay does not have.
Who should pick which
Pick Firefox Relay if replying from the alias and open source code matter most to you, and 5 free aliases is enough while you decide on a paid plan. Pick Email Monster if you want a larger free tier, readable custom names, and newsletter digest bundling without an extension.
Frequently asked questions
How many free aliases does Firefox Relay offer?
Firefox Relay's free plan is limited to 5 email masks. Email Monster offers unlimited aliases on its free plan with a cap of 40 forwarded emails a month.
Does Firefox Relay work outside of Firefox?
Relay's extension is built for Firefox, though the dashboard works in any browser. Email Monster's addresses are plain email addresses that work anywhere without installing anything.
Can Email Monster reply from an alias like Firefox Relay can?
No. Firefox Relay supports replying from a mask on paid plans. Email Monster forwards mail to your real inbox but does not currently support replying from the alias address.
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No credit card required. Unlimited aliases on your own subdomain.