Privacy forwarding

Permanent privacy aliases such as DuckDuckGo Email Protection are not disposable mailboxes. Forwarding detection does not change their disposable verdict or confidence score. Plus-addressing alone is not forwarding evidence.

Paid plans include forwarding and blocked on valid-format single checks automatically. Bulk checks use the same classification and policy. The default allows privacy relays. Free and anonymous checks include disposable detection, without forwarding metadata or relay controls.

Configure your integrations

• Settings → Validation: set the account default.
• API Keys: open a key's Settings to inherit the account default, allow relays, or reject them.
• Playground: try a setting without changing saved defaults.

Precedence: request option → key override → account default → allow. Keys inherit unless explicitly changed. A downgrade suspends paid settings; saved preferences remain for a later upgrade.

Request override

Send block_privacy_relays with a single or bulk email/domain request:

Value	Behavior
Omitted	Use saved defaults.
true or 1	Reject known privacy relays.
false or 0	Allow privacy relays; detection stays on.

Use a query parameter, JSON boolean, or form field. Invalid values return 422; an explicit option without paid access returns 403. An unavailable rejection policy is never silently ignored.

curl --fail-with-body --max-time 10 \
  -H "X-Api-Key: $DISIFY_API_KEY" \
  https://disify.com/api/email \
  --data-urlencode 'email=example@duck.com' \
  --data-urlencode 'block_privacy_relays=true'

Keep API keys on your backend. See Quick Start for complete timeout and HTTP error handling.

A completed single check returns HTTP 200, including when blocked: true. Your integration must enforce that decision.

Interpret the result

Illustrative partial response with relay rejection enabled:

{
  "format": true,
  "domain": "duck.com",
  "disposable": false,
  "forwarding": {
    "detected": true,
    "type": "privacy_alias",
    "provider": "duckduckgo",
    "matched_by": "domain"
  },
  "blocked": true
}

forwarding.detected is true for a known match, false for no known match, or null when detection is inconclusive. The other forwarding fields identify the provider and match method; see Response Fields.

Input and setting	disposable	forwarding.detected	blocked
Known permanent relay, allowed	false	true	false
Known permanent relay, rejected	false	true	true
No disposable evidence; relay check inconclusive, rejection enabled	false	null	null
Disposable evidence, any relay setting	true	Depends on the forwarding check	true

Check HTTP status, format, and dns alongside blocked. When enforcing relay rejection, require blocked === false; missing or null is not an allow decision. A positive disposable result still blocks if forwarding is inconclusive.

A negative forwarding result means no known match, not proof that the address never forwards. These checks do not establish mailbox existence, deliverability, or the destination behind an alias.

Provider coverage

Provider ID	Reviewed address domains	Dedicated MX detection for custom domains
duckduckgo	duck.com	No
simplelogin	simplelogin.com, slmail.me, aleeas.com and its subdomains	mx1.simplelogin.co, mx2.simplelogin.co
proton_pass	passmail.net	Custom domains on SimpleLogin infrastructure report simplelogin
addy	anonaddy.com, anonaddy.me and their subdomains	mail.anonaddy.me, mail2.anonaddy.me
firefox_relay	mozmail.com and its subdomains; relay.firefox.com	No; shared mail infrastructure is insufficient evidence
apple	privaterelay.appleid.com	No
thirty_three_mail (33mail)	Customer subdomains of 33mail.com; excludes the root	domains.33mail.com, smtpv2.ec2.33mail.com
manyme (ManyMe)	manyme.com	No
cloaked (Cloaked)	cloak.id	No
paced_email (Paced Email)	daily.paced.email, weekly.paced.email, monthly.paced.email	No
alias_email (Alias Email)	bumpmail.io	No

Subdomains are matched only where listed. Custom-domain MX detection requires all returned MX hosts to belong to the same reviewed provider. A custom domain can still have independent disposable evidence; forwarding MX does not erase that evidence.

Masked addresses can share icloud.com and Fastmail domains with ordinary addresses. These domains, general business forwarding, and shared mail infrastructure alone are not privacy-alias evidence.

The classification follows provider documentation: DuckDuckGo alias lifetime, SimpleLogin's distinction from disposable mail, Proton aliases, addy.io custom domains, Firefox Relay, and Apple private relay.

Bulk and analytics

Bulk jobs keep the settings and paid access captured at submission, even if the account or key changes later. Valid-result lists exclude relay rejections and inconclusive policy results.

Analytics reports recorded paid forwarding checks separately from disposable detections. The two classifications can overlap on custom domains.