prevent the new MS365 Outlook to send emails automatically

Dear Leendert Pengel,

Thank you for posting your question on the Microsoft Q&A forum.

From my understanding, you would like the new Outlook to provide the same Work Offline or manual send/receive control (keep emails in the Outbox or prevent Outlook from sending messages immediately) that was available in Classic Outlook, so emails do not send automatically while you are online

If my understanding is not correct, please feel free to let me know. I’ll be happy to clarify further.

However, at this time, the exact “Work Offline” or manual send control behavior from Classic Outlook is not available in the new Outlook experience.

As a closest alternative, you may use Schedule send instead of clicking Send directly. This allows you to control when a specific message is delivered, although it does not provide a global offline mode like before.

If this level of control is critical for your workflow, the only full solution currently available is to switch back to Classic Outlook, which remains fully supported and available.

The new Outlook is still actively evolving, and Microsoft continues to enhance it based on customer feedback. If this functionality is important for your business needs, I strongly encourage you to share your suggestion through the Microsoft Feedback Portal, as customer input directly influences future improvements.

I hope this information helps. If you have any additional questions, please feel free to let me know.

If you need further clarification, please click Comment.

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In new Outlook for Windows, messages are sent automatically by default when the device is online and the Send button is selected. This behavior matches classic Outlook and does not require additional configuration.

To immediately force sending/receiving (for example, after composing several messages):

1. Go to Mail in the navigation bar.
2. On the View tab, select Sync.
3. Alternatively, press F9 to manually trigger sync.

During this sync, new messages are sent and incoming mail is retrieved. There is no separate “Send/Receive Groups” configuration in new Outlook; the classic Send/Receive tab has been replaced by the Sync feature.

References:

• Sync to manually check for new mail and to send messages in Outlook