Email Not Sending? How to Fix Outgoing Mail Problems

You hit send and the email sits in your outbox. Or it bounces back with a cryptic error. Outgoing email failures are one of the most common problems we fix remotely — and usually it's a simple settings issue, not a broken computer.

Check the Basics First

• Internet connection: Open a web browser and load any website. If that fails, you have a connectivity problem, not an email problem
• Recipient address: A single typo in the email address causes a bounce. Double-check the address, especially the domain after the @
• Attachment size: Most email providers cap attachments at 25MB. Try sending without the attachment to test

Common Error Messages

"Authentication failed" or "Password incorrect"

Your email password may have changed (especially after enabling 2FA) or your app needs an "App Password" instead of your regular password. Gmail, Yahoo, and Outlook all require app-specific passwords when 2FA is enabled.

"SMTP server not responding"

The outgoing mail server settings are wrong or the server is down. Check your SMTP settings: server address, port (usually 587 for TLS or 465 for SSL), and encryption type. Your email provider's help page has the exact settings.

"Relay access denied" or "550 error"

The mail server thinks you're not authorized to send through it. This happens when you're on a different network than usual (hotel Wi-Fi, VPN) or your ISP blocks port 25. Switch to port 587 with authentication.

Fix by Email Provider

Gmail

1. Go to Gmail Settings → See all settings → Accounts and Import
2. Under "Send mail as," check that the sending account is correct
3. If using a desktop client (Outlook, Thunderbird), enable "Less secure app access" or create an App Password at myaccount.google.com/apppasswords

Outlook/Microsoft 365

1. File → Account Settings → Account Settings → double-click your account
2. Click "More Settings" → Outgoing Server tab
3. Check "My outgoing server (SMTP) requires authentication"
4. Use: smtp.office365.com, port 587, TLS encryption

Apple Mail (Mac)

1. Mail → Settings → Accounts → select your account → Server Settings
2. Under Outgoing Mail Server, verify the SMTP server and port
3. Uncheck and recheck "Automatically manage connection settings"

When to Get Remote Help

If you've checked the basics and the error persists, it could be a firewall blocking outgoing mail, antivirus software interfering with SSL/TLS, or a corrupted email profile. These are quick fixes via remote session — usually under 30 minutes.