Recognize repeat trial addresses in your own records
identity.normalized_email and fingerprint collapse plus-tags and Gmail dot variants, so a new trial address can match a record you already hold. Add disposable and new-domain flags before granting the trial.
Evidence for your trial policy
EmailScore returns the facts; your application decides what a repeat looks like.
Normalized identity
Compare identity.normalized_email or its fingerprint against the trials you already granted. Matching stays in your database, under your rules.
Disposable and new domains
DISPOSABLE_DOMAIN, ZERO_DAY_DOMAIN (registered 30 days ago or less, when on record) and VERY_YOUNG_DOMAIN (31 to 89 days) arrive with the same verdict.
Your policy
Require a card, confirm the email, or shorten the trial for a challenge. Keep a path for real users whose addresses happen to look unusual.
Practical questions
Is an alias proof of abuse?
No. People use plus-tags and aliases for privacy and organization. Treat a match as a reason to look closer, not as a verdict on the person.
Which variants are normalized?
Plus-tags are removed for every domain. For Gmail and Googlemail, dots in the local part are also removed and the domain is folded to gmail.com. The original address is always returned alongside the normalized one.
See the normalized identity for an address
Run a check and open the Address strip to see the normalized address and fingerprint.