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33Mail vs Firefox Relay: catalog facts
33Mail	Firefox Relay
Best for: Disposable email forwarder offering unlimited free aliases	Best for: Email masking service from Mozilla that forwards aliases to your real inbox
Free Free for unlimited aliases on the 33mail subdomain.	Free + paid options Free tier with a limited number of masks, paid plan for unlimited masks and a custom domain.
Web	Web, Browser extension
Unlimited free aliases on the service's subdomain Simple to create a new alias on demand for any signup	Backed by Mozilla, a long-standing name in browser privacy Simple mask creation directly from the browser
Aliases live on 33mail's shared subdomain rather than a custom domain on the free tier Long-running service with a dated interface compared to newer alternatives	Free tier limits the number of masks available Deeper integration is tied to the Firefox browser ecosystem
Web application	Web application, Browser extension
Not open source	Not open source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Sources for 33Mail 33mail.com Catalog checked September 22, 2026	Official website Full listing and sources Sources for Firefox Relay relay.firefox.com Catalog checked September 22, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.