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Articles, guides and glossary
Blog
- What a catch-all domain means for your list
- How to keep cold email bounces under 2%
- Open source email verification vs an API: honest trade-offs
- Email deliverability: the complete guide for 2026
- How to Choose the Best Email Verification Tool for Your Team
- AI SDR email verification: guardrails before an agent sends
- How SimpleCold handles slow mail servers
- Lead gen agency email verification: protecting client domains
- Migrate your email list to a new ESP without a bounce spike
- Email Address Validation Test Cases: Edge Cases Forms Get Wrong
- HubSpot email validation: native checks and a bulk clean-up
- Built-in sequencer verification vs a standalone email verifier
- Undeliverable email: what it means and how to read the report
- How to verify catch-all emails: what works and what doesn't
- Email Validation in PHP and Laravel: filter_var, DNS and APIs
- How to find email addresses for companies, then verify them
- How to email an old email list without burning your domain
- How to validate emails in Excel and Google Sheets
- How SMTP email verification works: the RCPT TO handshake
- Waterfall Email Verification: Does Stacking Verifiers Help?
- How to reduce bounce rate in email marketing: 10 fixes
- Real-time vs bulk email verification: which do you need?
- Unknown email verification results: why they happen
- Email hygiene best practices: a recurring list cleaning checklist
- Cold Email Deliverability: The Setup Checklist
- Sender reputation: what it is, how to check it, how to fix it
- Email validation in Python: syntax, MX records and mailbox checks
- Email list cleaning checklist: before, during and after a send
- What is an MX record? How to look one up and what errors mean
- GDPR and Cold Email: What B2B Senders Need to Know
- SMTP 550 error and other bounce codes, explained
- How to block disposable emails at signup without losing real users
- How often should you clean your email list?
- Apollo emails bouncing? Why exported leads bounce and what to do
- Common Email Typos (gmial.com, hotmial.com) and How to Catch Them
- What is a good email bounce rate? Benchmarks and thresholds
- Why we show a reason instead of a score
- Cleaning a Mailchimp audience before a big send
- How to warm up a new domain for cold email without burning it
- What Is a Spam Trap? Types, Causes and What Verification Catches
- Email validation in JavaScript: browser, Node.js and beyond
- B2B data decay: why your contact list goes stale and what to do
- Email validation vs verification: what each one actually checks
- Should you send to catch-all emails? A risk framework
- SPF, DKIM and DMARC Explained in Plain Words
- How to validate an email address: 5 free ways that work
- Role-based emails: send or skip?
- Gmail and Yahoo bulk sender requirements, explained
- How to verify an email address without sending an email
- Email Validation Regex: The Pattern You Should Actually Use
- How to verify emails before cold outreach, step by step
- Hard bounce vs soft bounce: what each means and what to do
- How to clean an email list: a 7-step process that holds up
- Why do emails bounce? Common causes and how to fix each one
- What Is Email Verification? How It Works, Step by Step
Developer guides
- Map verification categories and statuses to send decisions
- Clean a CRM export with the bulk API and re-import the results
- Error handling and rate limits for the SimpleCold API
- Polling patterns for bulk jobs and pending checks
- Handle processing and no-response results correctly
- Run a bulk verification job end to end
- Verify a list of emails in Python with the batch endpoint
- Verify emails at sign-up with Node.js
- Test your integration with free test email addresses
- Quickstart: verify your first email with the SimpleCold API
Glossary
- Bounce rate
- Catch-all domain
- Disposable email
- DKIM
- DMARC
- Double opt-in
- Email deliverability
- Email syntax
- Email validation
- Email verification
- Email warm-up
- Greylisting
- Hard bounce
- List decay
- List hygiene
- MX record
- Null MX
- Plus addressing
- PTR record
- Role-based email
- Secure email gateway
- Sender reputation
- SMTP handshake
- SMTP status codes
- Soft bounce
- Spam complaint rate
- Spam trap
- SPF
- Suppression list
- Typo domain