Showing posts with the label o365

Microsoft to limit sending from onmicrosoft.com

When you spin up a Microsoft 365 environment to handle email for your corporate or other organization, the system assigns you a default email domain that looks like something.onmicrosoft.com. This subdomain (with your Microsoft environment tenant name in it) is meant as a placeholder until you set up your real domain name for email. It gives admins a test platform to do a bit of email sendi…
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Microsoft Exchange Online adding inbound IPv6 support

Do you host your domain's email service on Microsoft Exchange Online/Microsoft 365? If so, you should note that IPv6 support is coming , and that Microsoft is enabling that support automatically. Starting on October 16th: "After [Microsoft] enables IPv6 for your Accept…

Microsoft: Decoding hidden spam-related headers

Did you know that Microsoft Outlook.com and O365 emails include special headers that break down the spam filtering results for email messages? These headers can help you decode the Spam Confidence Level (SCL), Phish Confidence Level (PCL) and Bulk Confidence Level (BCL) values …

Exchange Online external recipient limits are coming

Microsoft recently announced that Exchange Online -- the email (and calendar, contacts and tasks) functionality provided in Microsoft 365 and Office 365 , will be subject to outbound email rate limits as of January 2025. That "external recipient rate limit" will be 2,…

All the different bounces you can get from O365

Bounce message. SMTP rejection. Deferral message. Non-delivery report (NDR). 5xx error. 4xx error.  No matter what you call them, there are a zillion different kinds of them out there. Heck, Microsoft's got at least four different ways to tell you "user unknown ."…

Microsoft: 451 4.7.500 Server busy delays on Wednesday 10/11

Today, Wednesday, October 11th, many senders are reporting trouble (specifically, delayed mail) when attempting to send email to Microsoft-hosted subscribers. Here's more on the issue from Steve Atkins from Word to the Wise .  I'm keeping a close eye on my Office365 adm…