Is devnull.facebook.com valid?

devnull.facebook.com is a domain that should be blocked from sign-ups or registrations. Based on our analysis, you should block this domain. If a user is trying to sign-up using an e-mail on this domain, it's likely that it's a malicious or fraudulent attempt.

Raw API JSON response:

{
    "valid": true,
    "block": true,
    "domain": "devnull.facebook.com",
    "base_domain": "facebook.com",
    "text": "Should be blocked",
    "reason": "Blacklisted",
    "risk": 65,
    "is_disposable": false,
    "is_email_forwarder": false,
    "is_public_free": false,
    "is_public_premium": false,
    "is_business_provider": false,
    "is_isp_email": false,
    "is_email_api": false,
    "is_web_hosting_email": false,
    "is_self_hosted": true,
    "is_parked": false,
    "is_role_based_email": false,
    "mx_host": "smtpin.vvv.facebook.com",
    "mx_ip": "173.252.87.251",
    "mx_info": "Using MX pointer smtpin.vvv.facebook.com from DNS with priority: 10",
    "mx_fallback": false,
    "mx_hosts": [
        "smtpin.vvv.facebook.com"
    ],
    "mx_ips": [
        "173.252.87.251"
    ],
    "mx_priorities": {
        "smtpin.vvv.facebook.com": 10
    },
    "email_provider": null,
    "disposable_provider": null,
    "possible_typo": [],
    "domain_age_days": null,
    "domain_created_at": null,
    "block_status_changed_at": "2020-12-13T21:17:36+00:00"
}