Disclosure: we built and maintain the tool in this post (email-list-cleaner, MIT). This article was written with AI assistance and reviewed by us.

Bounces hurt sender reputation, and many "list verification" services require uploading your contacts to a third party. If you just need to catch the obvious problems, you can do it on your own machine with a zero-dependency Node.js CLI.

Repo: https://github.com/5012763083a-oss/email-list-cleaner

What it checks

Syntax : is the address well-formed?

MX lookup : does the domain publish mail servers? Public DNS only, with no SMTP probing , so no mail server is contacted.

Disposable domains : flags throwaway inbox providers.

Role accounts : flags info@ , admin@ , support@ and similar addresses.

Typos : suggests fixes like gmial.com → gmail.com .

Duplicates : removed case-insensitively.

Nothing in your list leaves your machine.…