Category: Blog

A PTR record maps a sending IP address back to a hostname, the reverse of what an A record does. Here is how reverse DNS and the FCrDNS check work, why Gmail and other mailbox providers require a valid one, who actually controls it, and how to set and verify yours.

Customer.io alternatives compared: Braze, Iterable, Encharge, Loops, Brevo, and MailerLite, with verified pricing, fit, and where each falls short.

Litmus quietly moved its Plus plan to a $500/month Core tier in August 2025, a roughly 151% increase, and stopped publishing self-serve pricing beyond it. Here are seven alternatives for teams re-evaluating their email QA stack, from like-for-like preview suites to developer-first testing tools.

At 100,000 emails/month, SES costs ~$10 and SendGrid costs $34.95-$89.95. See the full pricing, deliverability, and setup comparison.

SendGrid vs Mailchimp compared for 2026: pricing, deliverability, API depth, and marketing automation, with a clear verdict by use case.

Resend and SendGrid both send transactional email reliably, but they come from different eras of tooling. A side-by-side on DX, React Email, pricing, and deliverability, verified as of July 2026.

A roundup of email deliverability tools by category: seed testing, reputation monitoring, DMARC management, and warmup, with pricing verified July 2026.

Constant Contact’s per-contact pricing climbs fast and its automation stays newsletter-first. Compare 8 alternatives with July 2026 pricing and how to pick one.

Best Klaviyo alternatives for 2026, compared for ecommerce and SaaS teams: Omnisend, Drip, Brevo, Customer.io, MailerLite, and more, with current pricing.

When an unsubscribe link is legally required under CAN-SPAM and GDPR, how it relates to the List-Unsubscribe header, and how fast you must honor requests.

A receipt email confirms a payment succeeded and gives the customer a record of it: the amount, the date, a transaction ID, the payment method masked to the last four digits, and a support contact. This guide covers the required fields, how fast to send it, marketing-content limits, and a copy-paste template.

A 550 SMTP reply means the message was permanently rejected. Here is what the common variants (5.1.1, 5.7.1, 5.7.26, and more) mean, how to tell whether the problem is on your side, and how to fix each one.