A purchased or scraped list is a starting point, not a send list. Data goes stale: companies close, rebrand and change what they sell, and people change jobs. One discussion on r/coldemail put the unusable share of a typical bought or scraped list at 50–70% (source). Whatever the real number for your list, assume a big chunk shouldn't be emailed until proven otherwise.
Load the website. Dead domain, "for sale" page or an empty placeholder? Cut it. Redirects to another brand? Update the company or cut it.
Industry tags from data providers are often wrong or out of date. Read the homepage headline. If it doesn't match your ICP, drop the row or downgrade it.
A perfect title at a company ten times your target size is a different sale. Check the employee count and country against your range.
Look for decision-making titles: owner, founder, partner, director, head of. Interns and assistants, or role inboxes like info@, mean the company may be good but the contact isn't. Mark it Silver and find the right person.
Remove invalid formats and duplicates. Be careful with free-email addresses and emails whose domain doesn't match the company website. Run a dedicated email verifier before any large send.
Gold first, in small batches from a sending tool with warmed inboxes (such as Smartlead or Instantly), with real personalisation. Fix Silver contacts before sending. Don't "test" Cut rows. Use the Gold/Silver/Bronze template to keep the grading consistent, and see the full cleaning checklist.
ListGrader loads every website, flags dead, parked and redirecting domains, catches role, free, invalid and duplicate emails, and grades fit against the ICP you describe.