Last updated: March 5, 2026
Microsoft Outlook may fail to send emails, showing errors like "Send/Receive Error", keeping emails stuck in the Outbox, or displaying server connection errors. This affects both desktop and web versions of Outlook.
Internet connection: Outlook needs stable internet to send emails.
Large attachments: Files exceeding the size limit (25MB for most accounts) block sending.
Outbox stuck: Emails may get stuck in the Outbox due to formatting or size issues.
Account authentication: Your password may have changed or expired.
Server settings wrong: Incorrect SMTP settings prevent sending.
• Make sure you're connected to the internet.
• Check if you can browse websites normally.
• Try sending from Outlook on the web (outlook.live.com) to isolate the issue.
• Go to the Outbox folder and open any stuck emails.
• Check if attachments are too large (over 25MB).
• Delete the stuck email, reduce attachment size, and try again.
• Go to File > Account Settings > Account Settings.
• Select your email account and click "Repair".
• Re-enter your password when prompted.
• Check if "Work Offline" is enabled in the Send/Receive tab.
• If it's highlighted, click it to go back online.
• Outlook won't send emails while in offline mode.
• Go to Control Panel > Mail > Show Profiles > Add.
• Create a new profile and set up your email account.
• Set the new profile as default and restart Outlook.
• Go to Settings > Apps > Microsoft Office > Modify > Repair.
• Choose "Online Repair" for a thorough fix.
• Restart your computer after the repair completes.
If emails still won't send, contact Microsoft support at support.microsoft.com or your IT administrator for work accounts.
Q: Why are my emails stuck in the Outbox?
A: Usually due to large attachments, lost internet connection, or authentication issues. Open the stuck email, reduce its size, and try again.
Q: What's the maximum attachment size in Outlook?
A: 25MB for Outlook.com and most Exchange accounts. For larger files, use OneDrive and share a link instead.
Q: Can I recall a sent email in Outlook?
A: In the desktop app with Exchange, go to Sent Items > open the email > Message tab > Actions > Recall This Message. This only works if the recipient hasn't read it yet.
Q: Why does Outlook keep asking for my password?
A: Your password may have changed, or your authentication token expired. Re-enter your credentials or enable modern authentication.