New: More detailed bounce activity and improved webhooks

By rahmat hidayat

Thursday, September 25, 2025

Plus, the MailerSend MCP now supports ChatGPT integration View in browser  Hey MailerSenders,  We're gearing up for Q4 with plenty of new updates to improve the experience of some popular features. We've got all the newness below, plus our usual content and resource shares. 👇  Deferred status is here with more detailed bounce info Introducing webhooks 2.0—lighter and faster This month's updates Guide to SMTP ports Deferred status is here with more detailed bounce info Ever had an email stuck as "Sent" and no idea why? Well, now email activity gives you a more accurate representation of where your email is at with the new Deferred status, available for Starter plans and above. What is a deferred email? Not delivered and not quite a bounce—deferred emails have been temporarily delayed from being delivered. Why? This is usually caused by a temporary issue on the recipient server, like a full mailbox or network connection issues. When an email's activity shows as Deferred, that means our system is retrying delivery for a set retry period. This will continue until the email is eventually delivered or the retry window closes, resulting in a bounce.  Additional visibility into bounce reasons You can now also see more detailed information about why emails are deferred or bounced.  A summary of the reason can be found on the Activity page, and you can view the full reason, including SMTP code and message, via webhook using the new activity.deferred event.     Check out our article by hitting the button below, or head to our help guide for an in-depth look at how to handle deferred emails and the SMTP codes and messages.  Learn more about the new Deferred status Introducing webhooks 2.0 Webhooks just got an upgrade. This latest update makes webhook payloads lighter for better, faster performance. We got rid of unnecessary additional data, which led to excess database queries. This results in faster webhooks and reduced load on the system for sharper performance and less redundant data to deal with.    You can choose between webhooks 2.0 (Recommended) and 1.0 (Legacy) when you create a webhook. All new webhooks will have 2.0 selected by default.  Click below to learn more about the new webhooks version.     Check out webhooks 2.0 Latest updates Our MCP now supports ChatGPT: Pro and Plus plan users of ChatGPT can now connect the MailerSend MCP. Check out our help guide to learn how.  Find the MailerSend API on SwaggerHub: Explore the endpoints, test requests and integrate transactional email features more easily. Check it out.   SMTP ports guide Navigating the sometimes confusing land of SMTP ports isn't very exciting. But it's crucial to understand the different ports and the role they play in email delivery to ensure secure, reliable sending.  In this article, we break down what each port does, why you should avoid using certain ones, and which you should use for safe email delivery. Plus, we also cover encryption, authentication and troubleshooting tips to help you avoid common issues.   Read the SMTP ports guide Customize your plan with add-ons Need more domains or data retention? You can customize your plan with add-ons for email verification credits, phone numbers (U.S. & Canada only), domain spaces, dedicated IPs, and activity data retention.  To check out or purchase an add-on, head to Plan & billing and click the Add-ons tab. Go to add-ons Have a great day, Content Writer MailerSend 228 Park Avenue South PMB 54955 New York, NY 10003 You received this email because you signed up on our website. Unsubscribe | Update preferences

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