Email verification & deliverability, for developers
Practical guides with working code: verify addresses, block fake signups, fix SPF, DKIM and DMARC, and keep bounces low.
Block Disposable Emails in Better Auth (MailRambo Setup)
Add MailRambo's Better Auth plugin to screen email/password signups. Free fast checks, fail-open errors, setup, compatibility and privacy explained.
Block Disposable and Fake Emails in Firebase Authentication
Reject throwaway and non-existent emails with a Firebase beforeUserCreated blocking function. Full TypeScript example, fail-open policy and free testing.
Block Fake and Disposable Signups in Supabase Auth
Use Supabase's "Before User Created" auth hook to reject disposable and non-existent emails before the account exists. Full Edge Function example.
DMARC Policy: Moving from p=none to Quarantine to Reject Safely
A staged DMARC rollout: start at p=none with reports, fix alignment for every sender, ramp quarantine with pct, then reject. Example records included.
Catching Email Typos at Signup: gmial.com, hotmial.com and "Did You Mean" UX
Email typos like gmial.com cost you users and cause bounces. How to detect them at signup with a free fast check and show a "did you mean" suggestion.
Email Verification in Laravel and PHP: Validation Rules, Fast Checks and Queues
Verify emails in Laravel with a custom validation rule, a free fast check at signup, a queued full check afterwards, caching, and a plain PHP curl example.
Email Verification Pricing Explained: Per-Check, Subscriptions and Expiring Credits
How email verification pricing works - per-check packs vs monthly plans, expiring credits, charging for unknowns, minimums, and real cost per 1,000 and 10,000.
Gmail and Yahoo Sender Requirements: A Practical Checklist
What Gmail and Yahoo require from senders since February 2024 (SPF, DKIM, DMARC, one-click unsubscribe, spam rate) and where list hygiene fits in.
How Email Verification Works: Syntax, MX, SMTP and Catch-All
What an email verifier actually checks, layer by layer: syntax, domain and MX, disposable lists, the SMTP RCPT probe, catch-alls, greylisting and "unknown".
Real-Time Email Validation on Signup Forms (Without Adding Friction)
Validate emails on your signup form in real time with a free fast check: typo suggestions, disposable blocking, fail-open errors and a full check later.
Role-Based Email Addresses (info@, sales@): Send, Skip or Segment?
What role-based addresses like info@ and support@ are, why they matter for deliverability and compliance, and when to send, skip or segment them.
Stop Fake Signups in Clerk: Verify Emails Before sign-up
Keep disposable and fake emails out of Clerk with three layers - dashboard restrictions, a server check in a custom sign-up flow, and a user.created webhook.
How to Verify Email Addresses in Node.js (With a Real API, Not Just Regex)
Verify email addresses in Node.js with syntax checks plus a mailbox-level API call. Working Express and Next.js examples, error handling and free test keys.
How to Verify Emails in n8n, Make and Zapier (No-Code Workflows)
Add email verification to no-code workflows. Use the MailRambo n8n node, or call the API from Make and Zapier HTTP modules, and clean leads before they sync.
Email Verification in Python: Django and FastAPI Examples
Verify email addresses in Python with requests or httpx. Drop-in Django form validation and FastAPI signup examples with error handling and free test keys.
How to Block Disposable Emails at Signup (Next.js Example)
Stop fake and throwaway signups by blocking disposable email addresses on your server. A complete Next.js example, UX tips and why static domain lists aren't enough.
What Is a Catch-All Email Address (and Why "Risky" Results Cause Bounces)
Catch-all servers accept every address during verification, so the mailbox can't be confirmed. How catch-alls work, why they bounce, and how to handle them.
SPF, DKIM and DMARC Explained for Developers
A practical guide to SPF, DKIM and DMARC: what each record does, how they work together, example records, the 10-lookup limit, and how to get to p=reject safely.
How to Reduce Your Email Bounce Rate Below 2%
What counts as a good email bounce rate, why bounces hurt deliverability, and a practical checklist to get below 2% - verification, authentication and list hygiene.
Email Validation With Regex vs an API: What Regex Can't Tell You
Why regular expressions can't validate email addresses on their own, the regexes that actually work for syntax, and when you need an email verification API.
How to Clean an Email List Before a Cold Email Campaign
A step-by-step process to clean a cold email list - dedupe, verify, handle catch-alls and role addresses, check domains, and protect your sender reputation.
Run these checks from your code
Verify addresses at signup, clean lists and read SPF/DKIM/DMARC with one API call. 100 free verifications a month, test keys that cost nothing, and the API on every plan.