Question 1

What is email normalization?

Accepted Answer

Email normalization is the process of converting an email address to a canonical, consistent form. This includes lowercasing the domain and local parts, removing Gmail dots (which are ignored by Gmail), and stripping plus aliases (e.g. user+tag@gmail.com becomes user@gmail.com). Normalization helps identify duplicate email addresses that refer to the same inbox.

Question 2

Does Gmail ignore dots in email addresses?

Accepted Answer

Yes. Gmail treats dots in the local part of an address as insignificant — john.doe@gmail.com, johndoe@gmail.com, and j.o.h.n.d.o.e@gmail.com all deliver to the same inbox. This tool optionally removes those dots so you can detect duplicate Gmail registrations. This behavior applies to gmail.com and googlemail.com addresses only.

Question 3

What is a plus alias and why would I strip it?

Accepted Answer

A plus alias (also called subaddressing) lets users append a tag after a plus sign in their local part — e.g. user+newsletter@example.com. The tag is ignored by most mail servers, so the email delivers to user@example.com. Stripping plus aliases during normalization reveals when different-looking addresses belong to the same inbox, which is useful for deduplication and abuse prevention.

Question 4

Is email normalization the same as email validation?

Accepted Answer

No. Validation checks whether an address is syntactically correct (and optionally verifiable via DNS or SMTP). Normalization transforms a valid address into a canonical form. This tool performs basic syntax validation, then applies the selected normalization transformations to produce a deduplicated list.

các công cụ miễn phí dành cho lập trình viên web

Email Normalizer

Input emails (one per line)

Normalized (deduplicated)