ListSweep / Guides

Email list cleaning guides

Short, practical answers to the problems that show up when a list has been sitting in a spreadsheet or a CRM for too long. Every guide can be acted on with the browser tool — nothing here requires uploading a list.

• How to remove duplicate emails from a CSV Dedupe an email list in a CSV without uploading it: case folding, whitespace, Gmail aliases and the duplicate types a plain spreadsheet UNIQUE() misses.
• Why Gmail addresses with dots are duplicates Google ignores dots in Gmail addresses, so john.smith@gmail.com and jsmith@gmail.com are one inbox. What that means for dedupe, and where dot rules don't apply.
• Why is my cold email bounce rate high? High bounce rates on cold email usually come from dead domains in a scraped list, domain typos and role addresses — not from your copy. How to diagnose in order.
• Your email list bounced 30% — what to do first A 30% hard bounce rate means a third of your list was never deliverable. Stop sending, find the dead domains, remove them, then ramp back slowly. Step by step.
• How to clean a scraped email list Scraped lists carry duplicates, truncated addresses, obfuscated @ symbols, role accounts and honeypots. A practical cleanup order, plus the legal risk worth knowing.
• Common email domain typos, and how to fix them safely gmial.com, gmail.co, hotmial.com, .con — the typos that turn a valid customer into a bounce. How to repair them without “fixing” addresses that were already correct.
• Should you email role addresses? Role addresses like info@, sales@ and support@ deliver but almost never engage. Why they damage sender reputation, and the one case where keeping them is right.
• What an MX record check proves An MX lookup tells you whether a domain accepts email at all. It is the highest-yield filter for dead lists — and it cannot tell you whether a specific mailbox exists.
• A free email list cleaner with no upload Why uploading a client list to a random website is a real risk, what “browser-only” means technically, and what you can and cannot verify without sending the file anywhere.
• Merging two email lists without duplicates Combining a CRM export with a newsletter list: match on the canonical address, decide which record wins per field, and keep the earliest consent date.
• Disposable email domains on your list Mailinator, temp-mail and hundreds of throwaway domains accept your mail and never engage. How to detect them by domain, and why catch-alls make it harder.
• How many bounces before Google blocks you? Google publishes a spam-rate limit (0.3%) and defines bulk senders at ~5,000/day. Bounces aren't the published metric — here's what actually gets you throttled.
• Verify an email list without uploading it What can be checked client-side (MX, duplicates, typos, disposables) versus what genuinely requires sending data somewhere (mailbox existence, catch-all). An honest boundary.
• Cleaning a HubSpot or Mailchimp export Exports carry status fields that decide whether you may email someone. Filter to sendable status, strip system properties, then dedupe on the canonical address.
• Email list hygiene checklist A quarterly routine that keeps bounce and complaint rates low: suppress hard bounces, dedupe, verify domains, sunset non-openers, and record what changed.