Getting addresses out of messy text
Email addresses rarely arrive in a clean list. They sit inside sentences, headers such as From: Maria Ortiz <[email protected]>, signatures and forwarded chains. The extractor reads the text for the pattern of an address rather than for a layout, so it works the same in all of these.
Surrounding punctuation is removed: in (contact: [email protected]). the address is [email protected], without the bracket or the full stop. A mailto: prefix is ignored, and addresses in the middle of a long line are found as easily as those on their own line.
Domains and duplicates
Domain only turns each address into the part after the @, which is useful to see which organizations appear in a list. The summary below the result counts how many addresses each domain has, before duplicates are removed, so a domain with 40 addresses stands out.
Case is ignored when removing duplicates. Technically the part before the @ can be case sensitive, but mail providers treat it as case insensitive in practice. Turn Ignore case off if you need to keep both spellings.
Limits, and using the list responsibly
The tool checks the shape of an address, not whether it exists. It cannot tell you if a mailbox is real or active. It does not find addresses in images, and it skips hidden formats such as name [at] example [dot] com.
Collecting addresses is the easy part. Writing to people is covered by privacy and anti-spam laws in many countries, which usually require a lawful reason or consent, and a way to unsubscribe. This tool does not check any of that, so it is your job to.