Toolstack
100% Client-Side DNS-over-HTTPS

SPF & DKIM Record Checker

Verify email authentication records directly from your browser. Analyze RFC 7208 SPF lookup limits, duplicate records, dangerous "+all" qualifiers, and DKIM public key bits.

Quick test live domains:
Domain & Selector Lookup
Encrypted browser query via Google / Cloudflare DNS-over-HTTPS without proxy servers.

Why SPF & DKIM Are Critical for Email Deliverability

1. The 10-Lookup SPF Ceiling (RFC 7208)

RFC 7208 imposes a strict ceiling of 10 DNS lookups when evaluating an SPF record. Nested includes from marketing platforms (Mailchimp, Klaviyo, Zendesk) quickly cascade beyond this limit, triggering silent PermErrors.

2. 2024 Google & Yahoo Inbound Mandates

Modern email security mandates require published SPF and DKIM authentication with at least 1024-bit (preferably 2048-bit) keys. Without them, commercial emails to Gmail and Yahoo recipients face aggressive spam-filtering.

Frequently Asked Questions

Clear, concise answers to common questions about Base64 decoding, encoding, and specifications.

It performs direct client-side DNS-over-HTTPS (DoH) lookups using Google Public DNS and Cloudflare DNS APIs over encrypted HTTPS, analyzing TXT records directly in your browser without proxy servers.

Explore More Free Tools on Toolstack

Client-side developer utilities, image converters, calculators, and educational engineering guides.

Word Counter

Count words, characters with/without spaces, sentences, and paragraphs in real time with reading speed metrics.

Open Tool

PDF Compressor

Reduce PDF document file size directly in your browser with zero server uploads.

Open Tool

Image Compressor & Resizer

Batch compress and scale JPG, PNG, and WebP images with custom quality settings.

Open Tool

URL Encoder & Decoder

Encode and decode query strings, special characters, and parameters with RFC 3986 percent-encoding.

Open Tool

JSON Validator & Formatter

Beautify, validate, minify, and auto-fix JSON syntax errors with real-time line/column diagnostics.

Open Tool

HEIC to JPG Converter

Convert Apple iPhone HEIC and HEIF photos to high-quality JPG directly in your browser.

Open Tool