Email non-delivery report (NDR) and SMTP errors in Exchange …
Admins can learn about SMTP errors and non-delivery reports (also known as NDRs or bounce messages) that are generated in Exchange Online.
Find and fix email delivery issues as a Microsoft 365 for business ...
Jun 25, 2025 · As a first step in troubleshooting email delivery problems for Microsoft 365 for business, we recommend that you download and run Support and Recovery Assistant on the …
Fix NDR error "550 5.1.10" in Exchange Online - learn.microsoft.com
May 1, 2010 · A spammer sent a message to a non-existent recipient, and they falsified the From address so it appears the message was sent by your email address. The resulting bounce …
Contact Us - Microsoft Support
Contact Microsoft Support. Find solutions to common problems, or get help from a support agent.
Remove yourself from the blocked senders list and address 5.7.511 ...
Jun 11, 2024 · For more information, see Email non-delivery reports in Exchange Online. For these delivery failures, we provide the Office 365 Anti-Spam IP Delist Portal page at …
External senders - Troubleshoot email sent to Microsoft 365
Jul 28, 2025 · This article provides troubleshooting information for issues with sending email to inboxes in Microsoft 365 & best practices for bulk mailing to Microsoft 365 customers.
Outlook replies or forwards cause non-delivery error “Your message …
Mar 25, 2024 · Until the fixed build is available, please use Outlook Web Access (OWA) or New Outlook. To work around the issue, delete the autocomplete entry for the recipient that you got …
DSNs and NDRs in Exchange Server | Microsoft Learn
Apr 30, 2025 · APPLIES TO: 2016 2019 Subscription Edition When there's a problem delivering a message, Exchange sends an NDR to the message sender that indicates there was a …
Office 365 did not generate a non-delivery report (NDR) when I sent …
Oct 25, 2022 · Dear M365 experts I'm getting the issue with Exchange Online. When I sent an email (with recipient type was UserMailbox) to outside the organization ___@___.___ (wrong …
Sent email in Outlook.com comes back "delivery failed"
The recipient's server believes that the mail server or mail account that you're using is a source of spam. Try this fix: You can contact the support team for the recipient's email provider and …
Outlook app is not receiving emails as timely as they arrive in …
Jun 11, 2025 · Thank you for the detailed information regarding the delayed email delivery issue in your Outlook desktop app. Based on your responses and the nature of the delays which …
Sender Support in Outlook.com - Microsoft Support
Ask the recipient to add your email address to their Safe senders list. See how in Outlook and Outlook.com. Don't put all your email recipients in BCC. Don’t send too many emails at once, …
Self-help diagnostics for issues in Exchange Online and Outlook
Jun 25, 2025 · It's vital that administrators be able to diagnose and resolve issues quickly in Exchange Online and Outlook. To support this effort, the Exchange and Outlook support …
Exchange Online troubleshooting - Exchange | Microsoft Learn
Exchange Online troubleshooting This library of articles provides guidance to troubleshoot and fix errors that you may experience when using Exchange Online. For a complete list of articles, …
Office 365 email delivery error 5.7.1 - Microsoft Support
Download Center Microsoft Store support Returns Order tracking Certified Refurbished Microsoft Store Promise Flexible Payments Education Microsoft in education Devices for education …
E-Mail sending to Offcie/Microsoft365 customers not possible
Oct 11, 2023 · Current status: We’ve identified that specific IP addresses are being unexpectedly limited by our anti-spam procedures, causing inbound external email delivery to become …
I have distribution list mail delivery issue - Microsoft Q&A
Oct 16, 2024 · Describes an issue in an Exchange hybrid deployment in which email messages are not delivered to members of a dynamic distribution group. Provides a solution. Describes …
Having issues with email deliverability to Outlook - Microsoft Q&A
Jan 31, 2025 · Hi, For some reason, our main domain got in a couple of blacklists (according to some email deliverability test platforms) and we, from time time, go to spam and our clients …
Intermittent Email Delivery Failures - Microsoft Q&A
Aug 19, 2024 · Users intermittently experience email delivery failures with no clear pattern. Emails are sometimes delayed by several hours or fail to deliver without generating non delivery reports.
Microsoft 365 Customer Service and Support
The type of support Microsoft provides for consumers depends on the product you're calling about and if you have a product for home or for business use. It can also depend on if you want help …