The Deliverable Diary

If your emails are landing in spam, the cause is almost always one of seven things: missing or misconfigured authentication, a damaged sender reputation, a high complaint rate, a dirty or purchased list, a brand-new or cold-warmed domain, a content or link pattern that trips filters, or an SMTP provider that’s quietly making things worse. […]

A transactional email is an automated message triggered by something a specific person did, or something that happened to their account, and it carries information they’re expecting or that they need to complete an action. Receipts. Password resets. Shipping updates. Two-factor codes. The definition is the easy part. The interesting part is the line that […]

We’ve made several new enhancements to our email API features, designed to give you more control, better performance and greater flexibility when sending emails at scale. From scheduling emails in advance to dramatically improving throughput and sending large batches more efficiently, these updates make it easier than ever to integrate powerful email workflows into your […]

Short answer: Yes, Gmail is still blocked in mainland China in 2026, the same as it’s been since 2014. If you need to read your inbox, you’ll want a VPN, an international eSIM, or roaming. But if your real problem is sending (an app, a website, a CRM, a printer, or just Outlook trying to […]

The rules quietly changed in February 2024. If your unsubscribe guide is older than that, it’s giving you 2014 advice for 2026 inboxes. Here’s what happened. Gmail and Yahoo started enforcing new requirements for any sender pushing more than 5,000 messages a day to their inboxes. One of those requirements: a working one-click unsubscribe, implemented […]

Most email attachment size guides give you a number and call it done. The problem is that the number on the box isn’t the number that actually sends. Encoding adds weight, recipient servers have their own caps, and a 24 MB file can bounce off a 25 MB limit without ever reaching an inbox. This […]