Author: Saul

The List-Unsubscribe header is an email header field that lets mailbox providers render a native “Unsubscribe” button at the top of a message, separate from any unsubscribe link in the body. When paired with the List-Unsubscribe-Post header defined in RFC 8058, that button triggers a true one-click unsubscribe: the mail client sends an HTTP POST…

Email warmup is the practice of gradually increasing sending volume from a new domain or IP address so that Gmail, Outlook, Yahoo, and other mailbox providers build a positive reputation for you before you send at full scale. The method: start with tens or low hundreds of emails per day to your most engaged recipients,…

DKIM (DomainKeys Identified Mail) is an email authentication standard defined in RFC 6376 that lets a receiving mail server verify two things: the message was authorized by the owner of a specific domain, and the message content was not altered in transit. It does this through a public/private key pair: the sender signs outgoing mail…

Use port 587 with STARTTLS for virtually all application email submission. It is the standard submission port defined in RFC 6409 and requires authentication before accepting mail. If your network or firewall blocks 587, try port 465 (implicit TLS, re-standardized in RFC 8314) or port 2525 (a non-official but widely supported fallback). Port 25 is…

A complete reference guide to SPF record syntax: version tag, mechanisms (a, mx, ip4, ip6, include, exists), qualifiers (+ – ~ ?), the -all vs ~all choice, the 10-lookup limit, and annotated real-world examples.

The best MailerLite alternative depends on where the fit breaks down for your team. For transactional email, Postmark or MailerSend are the clearest upgrades. For SaaS lifecycle automation with event triggers, Loops or Customer.io handle product-driven workflows that MailerLite was not designed for. For developer teams wanting a clean sending API, Resend or Mailgun fit…

Spam traps are monitoring addresses used by mailbox providers and blocklist operators to catch senders with poor list hygiene. Learn the three types, how you end up hitting them, and the practical steps that keep your list clean.

Learn how to structure an HTML email with nested tables, modular sections, and a ~600px wrapper so it renders consistently in Gmail, Apple Mail, and Outlook.

An SMTP relay is a third-party service that accepts your outbound mail and handles the actual server-to-server delivery for you, including reputation management, bounce processing, and suppression lists. Here is how it works and when you need one.

A code-first tutorial covering table-based layouts, the fluid/hybrid approach, media queries, Outlook MSO ghost table caveats, and a minimal working responsive HTML snippet.

BIMI (Brand Indicators for Message Identification) is a DNS-based standard that lets you display your company logo directly in the inbox, next to your sender name. Gmail, Yahoo Mail, and Apple Mail show a verified logo when your domain passes strict authentication checks and, in most cases, holds a cryptographic certificate proving logo ownership. The…

Double opt-in requires new subscribers to confirm their email address before joining your list. Here is how it works, when to use it, and what GDPR says.