Six levels of similarity
Rather than treating comparison as a binary operation, Email Matcher returns one of six categorical levels — so every consumer can pick the strictness it needs.
Login validation needs EQUAL. Duplicate detection often accepts EQUIVALENT or MATCHING. Fraud-prevention surfaces want even SIMILAR addresses for review.
The matcher is part of Search Cluster and works alongside Name, Address and Telephone matchers.
From identical to clearly different
Byte-identical strings.
Different strings, same inbox — case differences, dotted Gmail variants, sub-addressing, alias domains (gmail.com / googlemail.com).
Same domain, similar local-part — john.doe@acme.com vs. john@acme.com. Strong likelihood of the same recipient.
Shared private domain or same local-part across domains — possibly related, requires context.
Some surface overlap, but no semantic relation.
Clearly different addresses.
Why two strings can deliver to the same inbox
Caseless local-parts
The domain is case-insensitive by spec; the local-part is case-insensitive in practice on every major provider.
Provider quirks
Gmail ignores dots in the local-part; some providers strip plus-tags. Two visibly different addresses route to the same mailbox.
Alias domains
@gmail.com and @googlemail.com are the same. So are several Microsoft and Yahoo legacy aliases.
Where Email Matcher fits
Login validation
Hard match required — only EQUAL grants access.
Duplicate prevention
Stop the same user creating two accounts via Gmail-dot tricks or plus-addressing.
Record matching
Reconcile customer records across systems with light tolerance for variation.
Fraud screening
Flag SIMILAR addresses for review — common pattern in account-takeover and synthetic identities.
Match e-mail addresses in your stack
We're happy to walk you through the API and recommend a strictness level for your use case.