Syntax, the domain's mail server, disposable domains and role accounts, checked in your browser. Honest limit: only an SMTP conversation can confirm a specific mailbox exists, and that needs a server. This catches everything before that step.
Privacy: this tool runs entirely in your browser. When you click Check, one DNS query for the domain you typed goes to Cloudflare's public DNS resolver (Google's as fallback). Nothing is stored, logged or sent to GrowthPal.
Inbox providers read your bounce rate as a confession: a sender who doesn't know if their addresses exist is a sender who scraped a list. Past roughly 2% bounces, deliverability starts sliding for every future send. That's why verification isn't optional hygiene; it's a core benchmark, and why every list we run gets verified before a single send.
Tools check the plumbing. The message is what your market answers. Get your TAM mapped, your ICP broken down and 5 angles written for your buyers, free.