Providers/Firefox Relay
Firefox Relay
Firefox Relay (Mozilla) creates email masks that forward to the user’s real address for privacy and inbox hygiene.
Relay masks can be legitimate users protecting their inbox. Use email_relay as a signal — challenge or allow based on your product’s abuse tolerance.
Example domains
Public domains commonly associated with Firefox Relay. ShieldSignup coverage is broader (marketing: 94,000+ disposable domains) — this page lists examples only, not every domain the provider may use.
- mozmail.com
- relay.firefox.com
Block with ShieldSignup
Call POST /v1/assess with the signup email. For known domains of this type, expect reason code email_relay and signals.email.relay_domain: true.
curl -sS -X POST https://www.shieldsignup.com/v1/assess \
-H "Authorization: Bearer sk_live_…" \
-H "Content-Type: application/json" \
-d '{"email":"user@mozmail.com","ip":"203.0.113.10"}'Related providers
SimpleLogin
SimpleLogin is a privacy-focused email alias / relay provider. Addresses forward to a real mailbox instead of being throwaway public inboxes.
AnonAddy
AnonAddy (addy.io) provides anonymous email aliases that forward to a real inbox.
DuckDuckGo Email Protection
DuckDuckGo Email Protection issues @duck.com aliases that forward to a private address.
Apple Hide My Email
Apple Hide My Email creates unique relay addresses that forward to the user’s iCloud inbox.