Email List Cleaner

How to use the email list cleaner

1. Paste your list in any common format.
2. Choose how far to normalise.
3. Review what was rejected, then copy the clean list.

About this tool

Takes a list in whatever form you have it — one per line, comma separated, or the `Name <address>` format mail clients produce — and returns a clean one.

Case handling is where the care is needed. Domains are case-insensitive by specification, so those are always lowercased. Local parts technically are case-sensitive, even though nearly every real provider treats them otherwise, so lowercasing them is offered as a choice rather than assumed.

Gmail's dot-and-plus folding is a third thing again, and it is off by default for good reason. Gmail ignores dots and everything after a plus, so `a.b+news@gmail.com` and `ab@gmail.com` reach the same inbox. That is a Gmail convention, not a rule — applying it to another provider's addresses would merge accounts belonging to different people.

Entries that are not recognisable as addresses are reported rather than silently dropped, and the domain breakdown is often the most informative output: a list dominated by one domain usually means it came from a single organisation.

Common uses

• Deduplicating a mailing list before importing it.
• Normalising addresses collected from several sources.
• Finding malformed entries that would bounce.

Frequently asked questions

Should I lowercase the whole address?

Domains, always. Local parts are technically case-sensitive, though nearly every provider ignores that, so it is offered as a choice.

What does Gmail folding do?

It removes dots and anything after a plus, since Gmail ignores both. It is off by default because it is a Gmail convention — applying it elsewhere would merge different people's addresses.

Does this check whether addresses are real?

No. It checks the shape only. The only way to know an address exists is to send to it, and no tool that avoids contacting a server can tell you more.