Outlook email not sending giving me amail delivery system reply.

Question

I use outlook classic for our business the email has recently not been sending some emails to random contacts

nothing in settings has changed.

why is this happening

Fiona

Answer 1

Hello, can you please share the bounce email? It contains important diagnostic data that helps shed some light of the root cause. Feel free to redact personal information when you share.

Answer 2

If you're experiencing issues with Outlook Classic not sending emails and receiving a mail delivery system reply, there could be several reasons for this problem. Here are some potential causes and solutions:

1. Email Account Issues: Check if there are any issues with your email account settings. Ensure that your account is properly configured and that your credentials are correct.
2. Outlook Profile Problems: Sometimes, a corrupted Outlook profile can lead to sending issues. You might want to create a new profile and see if the problem persists.
3. Email Size and Attachments: If the emails you're trying to send have large attachments, they may be failing to send. Check the size of the emails and try sending smaller ones.
4. Network Issues: Ensure that your internet connection is stable. A poor connection can prevent emails from being sent.
5. Antivirus or Firewall Settings: Sometimes, antivirus software or firewall settings can block outgoing emails. Check your security software settings to ensure that Outlook is allowed to send emails.
6. Updates: Ensure that your Outlook and Windows are updated to the latest versions, as updates can fix bugs that might be causing the issue.
7. Support and Recovery Assistant: You can use the Microsoft Support and Recovery Assistant to diagnose and fix issues related to Outlook. This tool can help identify problems with your account or Outlook settings.

If none of these solutions work, you may want to contact Microsoft support for further assistance.

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References:

• Help Identify My Issue with Sending/Receiving Email in Outlook (Automatic Checks)
• Find and fix email delivery issues as a Microsoft 365 for business admin