
Postmark (ActiveCampaign): Complete Technical Guide to Transactional Email
Detailed technical guide for developers: DNS configuration (DKIM, custom Return-Path), REST API vs SMTP, Message Streams, dedicated IP, webhooks and 2026 pricing.
REST APIs, webhooks, and programmatic DNS management.
7 articles

Detailed technical guide for developers: DNS configuration (DKIM, custom Return-Path), REST API vs SMTP, Message Streams, dedicated IP, webhooks and 2026 pricing.

A complete guide for developers and system admins: DKIM configuration via CNAME, choosing between API and SMTP, Mailchimp prerequisites, and pitfalls to avoid.

A detailed technical guide for developers: DNS configuration (SPF, 2048-bit DKIM with autorotation), REST API vs SMTP, dedicated vs shared IP, limits and webhooks.

Complete Amazon SES configuration with Easy DKIM, Custom MAIL FROM, strict DMARC alignment. Everything you need for optimal deliverability and GDPR compliance.

A comprehensive guide for developers and system admins: DKIM configuration, API v3 vs v3.1, dedicated vs shared IP, and pitfalls to avoid with Mailjet.

A detailed technical guide for developers: DNS configuration (SPF, 2048-bit DKIM), Web API v3, SMTP Relay, dedicated vs shared IP, limits and webhooks.

A comprehensive guide for developers and sysadmins: DKIM configuration, choosing between API and SMTP, technical limits, and pitfalls to avoid with Brevo.
DNS Lookup
Choose a DNS record type to search for.
Propagation & diagnostics
Compare resolvers worldwide and inspect returned answers.
Keep history, monitor your zones and automate recurring checks.
Email authentication
Tools to verify and validate your email authentication setup.
Deliverability
Email deliverability audit
Audit MX, SPF, DKIM and DMARC to confirm a domain is ready to send.
Mail header analyzer
Decode participants, authentication results and routing from raw headers.
Email tester
Send a test email and get instant authentication and deliverability feedback.
IP Blacklist Checker
Check if your IP is on email blacklists
Domain Blacklist Checker
Check if your domain is on URI blacklists
Text
Transform, encode and measure your content in seconds.
Text case converter
Convert any block of text to upper or lower case instantly.
Base64 encoder / decoder
Encode or decode any content in Base64 without leaving the browser.
Slug generator
Transform any sentence into an SEO-friendly slug in seconds.
Word & character counter
Measure the length of any text, with instant word and character counts.
Images
Preview and validate your BIMI logos before publishing.
Certificates
Inspect CSRs, BIMI logos and VMC certificates before you deploy.
IP
Look up addresses, owners, reverse records and ranges.