How do I fix Gmail SMTP?

Gmail SMTP allows users to send email using their Gmail accounts from other email clients or applications. However, it can occasionally encounter issues that prevent sending mail from external applications. There are a few troubleshooting steps that can help fix most Gmail SMTP problems.

How do I fix Gmail SMTP?

Check Your Network Connection

One of the most common reasons for Gmail SMTP failure is an unstable internet connection or network issues. Check your internet connectivity and make sure you are able to access other websites and services besides your email client. This will also rule out any temporary problems with your internet connection.

Troubleshooting steps:

  • Ping websites like to check your connection
  • Restart your computer or router if the problem persists
  • Check if other devices on the same network can access the internet

Ensure Your Gmail Account Allows Less Secure Apps

By default, Gmail blocks less secure third party apps from sending email through SMTP. You will need to enable the “allow less secure apps” setting to permit applications using SMTP to send mail as your Gmail account.

To enable it:

  1. Open Gmail settings
  2. Go to Account Access tab
  3. Toggle on “Allow less secure apps”

Then try connecting with your third party app again.

Recheck Third Party App Settings

Once you have enabled less secure apps in your Gmail account, double check the authentication settings and SMTP configuration in your email app or service that is trying to send mail through Gmail.

Some key things to verify:

  • SMTP server is on port 587
  • Authentication set to Normal Password
  • Have correctly entered Gmail address and password

Updating the settings properly should resolve most connection issues with other apps.

Check Authentication Credentials Again

One of the most common Gmail SMTP problems occurs when the username or password configured in the third party app become outdated or changed for your Google account.

Always reconfirm:

  • Gmail address is still actively used by you
  • App password if you have created one for the client
  • Primary account password if you have recently changed it

Resetting credentials usually resolves authentication failed errors.

Review Google Account Activity

When troubleshooting Gmail SMTP issues, checking recent activity on your Google account can reveal any suspicious, unauthorized or otherwise abnormal access attempts through SMTP or other protocols recently.

This can help narrow down if the SMTP problem is coinciding alongside potential security issues with your account that need addressing as well.

Some unusual activity to keep an eye out for:

  • Multiple failed login attempts
  • SMTP access from unrecognized locations
  • Unfamiliar device logins

Reviewing security logs is an important step in diagnosing Gmail SMTP problems.

Check If Connecting From Unusual IP Address

Google may automatically block unusual connection attempts to your Gmail account from an unknown IP addresses or regions.

For example, if you usually access Gmail just from home but are now trying SMTP from a new work laptop. The location mismatch may cause Google to block the connection.

Ways to fix include:

  • Temporarily allowing less secure apps
  • Adding the new IP to account access whitelist
  • Using OAuth 2.0 authentication option if available

Confirming the IP address causing issues is an authorized device usually resolves access denied errors.

Whitelist Third Party App or Device

For continued SMTP access from a verified third party email app or device, consider adding it to the authorized access list in Gmail security settings, under “Connected apps & sites”.

This will exempt the app from less secure access restrictions and generally allow reliable SMTP access going forward, preventing potential issues due to irregular connection attempts.

The only requirement is verifying and trusting the source first as a legitimate, low risk application needing SMTP logins.

Disable Two-Factor Authentication

As an extra security precaution for your Google account, two-step verification requires entering a code from your phone or authentication app when logging in from new devices.

Unfortunately, automated SMTP connections usually do not support entering 2FA codes. Temporarily disabling two factor authentication may be necessary to resolve SMTP issues in such cases.

Remember to re-enable two factor auth after troubleshooting SMTP connections for optimal security on your Google account going forward. Checking recent account activity before disabling is also advisable.

Try OAuth 2.0 Authentication Method

For supported email clients and apps, the most secure and reliable authentication method is OAuth 2.0. This allows logging into Gmail without directly using your Google account password.

Instead an app specific token is generated, which typically grants limited SMTP access. This avoids insecure app restrictions and is less likely to be blocked.

Check if applications you use offers OAuth options for connecting to Gmail. This usually resolves authentication issues for good and is more secure.

Confirm Port 587 Is Not Blocked

Enterprise firewalls or internet filters can sometimes block specific ports like 587 used for Gmail SMTP connections. Confirm whether you can access other common web services using port 587.

If the port seems blocked across multiple services including SMTP, speak to your system administrator about allowing communication on key ports like 587 for critical business applications including email.

Contact Gmail Support

For repeated SMTP connectivity issues after trying common troubleshooting steps, consider directly contacting Gmail support for further help identifying and addressing problems.

Provide relevant details like applications used, specific error messages, account activity checks done already. Support agents can check server side logs for anomalies and suggest alternative connectivity options.

They represent your best chance at resolving tricky persistent SMTP problems compared to standard troubleshooting.

Key Takeaways

  • Check network connections and Gmail account settings first when troubleshooting issues
  • Confirm less secure app access is enabled and third party app credentials are updated
  • Review recent Gmail account activity for suspicious logins possibly related to the problem
  • Whitelisting trusted apps can prevent repeat SMTP blocks from them
  • Consider OAuth 2.0 authentication for more secure and reliable connectivity
  • Contact Gmail support if problems persist after standard troubleshooting


Connecting to Gmail SMTP allows conveniently sending emails from non Gmail clients. However, users can encounter frustrating access issues or authentication failures at times preventing outbound messages. By methodically checking common account, network and application factors – the vast majority of Gmail SMTP problems can be self diagnosed and resolved with some diligent troubleshooting. For particularly tricky cases unable to be fixed after several tries, seeking assistance from Gmail’s knowledgeable support team is the best path to regaining dependable SMTP functionality.

Frequently Asked Questions

  1. What are the most common Gmail SMTP errors?
    Some frequent Gmail SMTP errors include authentication failed, SMTP server unavailable, connection timed out, invalid credentials, and access from unauthorized device or app blocked. 
  2. Why does Gmail not accept my password for SMTP connection?
    Typically an invalid password error for SMTP login is caused by changed or incorrect Gmail password configured in the email app, or if an app specific password being used has been recently reset. 
  3. Does Gmail block SMTP access from less secure apps?
    Yes, Gmail restricts SMTP connections by default from third party apps considered less secure unless you explicitly allow less secure app access. This is an important setting to check when troubleshooting SMTP issues. 
  4. Can two factor authentication cause problems with SMTP logins?
    Yes, since automated SMTP connections generally do not automatically enter 2FA challenge codes if prompted, having two factor authentication enabled on your Google account can directly disrupt SMTP functionality. 
  5. How can I tell if my Gmail SMTP issue is due to account security problems?
    Check recent activity on your Google account for any unauthorized, suspicious or unusual successful/failed logins, devices or locations indication a security breach which could be impacting SMTP as well. 
  6. Does Gmail block SMTP access from unknown IP addresses?
    Possibly. Gmail security systems automatically block any perceived suspicious activity, which could include an unfamiliar location like new device or irregular country sending SMTP requests before you have a chance to authorize it. 
  7. Should I whitelist apps needing SMTP access to my Gmail?
    Whitelisting specific trusted third party apps needing regular SMTP access can be good practice, as it permits logins from pre-authorized sources without less secure app restrictions that may disrupt connectivity. 
  8. How can I troubleshoot issues with port 587 blocked?
    Try accessing common web apps over port 587 to test if connectivity over that port works in general. If blocked across multiple services, request your network admin to open port 587 which is essential for supporting critical functions like external access to email systems. 
  9. When should I involve Gmail support for troubleshooting SMTP problems?
    If all standard troubleshooting steps for common issues have been exhausted in trying to diagnose and fix Gmail SMTP problems without success, reaching out to experienced Gmail support specialists should be the next step for deepest troubleshooting capabilities.

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