Clean a lead list, then find out who you have already emailed, so you write to the people you have not. Everything runs in your browser and nothing is uploaded.
Every file you drop here is read and processed in your browser. Nothing is uploaded, nothing is stored, and we never ask for access to your mailbox. A lead list is other people's names and email addresses, the safest place for it is your own machine. Closing the tab is all it takes to be rid of it.
A CSV with a header row. Drop several at once and they are merged, useful when you are bringing verified batches back together.
Three of the seven phases run in this tool. Two run inside your own Google account, and two happen somewhere else entirely. Here is all of it, including the script and the prompts.
Get a raw lead list out of wherever you find prospects.
Most verification services cap an upload. Split once, upload each part.
A deliverability check, which needs a service that actually sends probes.
Bring the verified batches back into one list, with duplicates gone.
The Apps Script route. Reads your Sent mail without it leaving your Google account.
The Takeout route, for when Apps Script is blocked by an admin.
Compare the two lists and leave with the file you actually write to.