Troubleshoot Outlook Not Sending Emails in Windows 10/11

In your Outlook Mail, you might not be able to send messages. It could be due to entering the wrong recipient’s email address, network problems, or using an outdated Outlook version. If that is the case, you can try these practical solutions to have the issue fixed without any stress:

Check if the Outlook Mail is Online

The Outlook Mail may be running in offline mode, and that could be the possible reason why emails are failing to send. To check if Outlook is offline:

Go to the Send/Receive tab.

Confirm that the Work Offline option is not selected.

Empty the Outbox

Open Outlook > Go to the Outbox folder.

Select the unsent or unnecessary emails > Move them to another folder or click Delete.

Compose a new email > Click Send to check if the issue is resolved.

Check Attachment Size

Outlook has a file size limit for attachments, typically ranging from 20MB to 25MB, depending on your account type. In case your attachment exceeds the limit, your message won’t be sent. So, you can either compress your attachment files or use a cloud storage service like Google Drive. Then you can copy the attachment links and email them. It won’t exceed the attachment's maximum limit.

Repair Outlook

On your PC, open Control Panel > Click Uninstall a program.

Select Microsoft Office from the list, then click Change at the top.

Click Yes on the User Account Control prompt.

Choose Quick Repair > Click Repair.

Source:- Troubleshoot Outlook Not Sending Emails in Windows 10/11