Gmail SMTP Plugin for WordPress

Last updated on by admin

Gmail SMTP is an advanced SMTP mailing plugin for WordPress for sending an email via Gmail SMTP server. Unlike most SMTP plugins It uses the OAuth 2.0 protocol to authorize access to the Gmail API instead of password authentication.

Gmail SMTP Benefits

1. Gmail SMTP plugin does not store your password. It uses the OAuth 2.0 mechanism for SMTP authentication. It means a more secure login system for users.

2. Gmail SMTP plugin uses PHPMailer – a very popular PHP library used in the core WordPress for sending an email. This is to make sure that users can still get full benefits of the default email functionality.

3. Gmail SMTP plugin takes a big headache away from you because you no longer need to Allow Less Secure Apps on your Gmail account. This is an option that users had to enable in order to fix SMTP connection issue. This issue went viral from December 2014, when Google started imposing OAuth 2.0 authentication to access their apps. This option affects SMTP mailing because applications that perform password authentication to IMAP, POP, or SMTP are considered Less Secure Apps.

As far as I know, this issue still affects almost all the SMTP plugins out there.

How OAuth 2.0 Authorization Works

1. You register a web application in the Google Developers Console.

2. When this application is launched it requests that you give it access to data in your Google account.

3. If you consent, the application receives credentials to access the API.


  1. PHP 5.4 or later
  2. A Gmail Account
  3. A self-hosted WordPress site

Gmail SMTP Info

Plugin Name: Gmail SMTP
Version: 1.1.2
File Format: application/zip
Requires: WordPress 4.8
Rating: 4.2 based on 48 votes
See All Ratings/Submit Your Rating Here
Price: 0 USD


You can install the Gmail SMTP plugin in one of the following ways:

Option 1 (Quick & Easy install)

  1. Go to Plugins->Add New from your WordPress admin dashboard
  2. Search for Gmail SMTP
  3. Click Install once you have found it

Option 2 (Manual install)

  1. Download the zip version of the plugin
  2. Go to Plugins->Add New
  3. Click Upload Plugin
  4. Select the zip file on your computer
  5. Install it

Gmail SMTP Configuration

In order to get started with the plugin go to Settings->Gmail SMTP from your admin dashboard.

screenshot of gmail smtp plugin menu

1. Go to

2. Login to your Google account which will be used to send an email.

3. Create a new project where your application will be registered.

screenshot showing how to create a new project in the Google Developers Console

It doesn’t have to be “Gmail SMTP Project 1”. You can name it whatever you like. I chose a meaningful name because I have multiple projects in it.

4. Once the project is created Click on the ENABLE API button.

screenshot showing how to enable an API on a project in Google Developers Console

If you have multiple projects make sure that the right project is selected in the drop down menu.

5. Select Gmail API under “G Suite APIs”.

screenshot showing how to select Gmail API for a project in Google Developers Console

6. This will show you more information as to what you can do by enabling Gmail API. Click Enable.

screenshot showing how to enable Gmail API on a project in Google Developers Console

7. Now that you have enabled this API you need to create credentials to use it. So go to the Credentials tab.

screenshot showing how to create credentials for Gmail API in Google Developers Console

8. Select OAuth Client ID when you are creating these credentials.

screenshot showing how to create OAuth Client ID for an API in Google Developers Console

9. In order to create an OAuth client ID, you need to set a product name first. So click Configure consent screen.

screenshot showing how to configure the consent screen when creating an OAuth Client ID

10. Enter a product name (e.g. Gmail SMTP) and a privacy policy page URL for the OAuth consent screen and click Save.

screenshot showing the oauth consent screen in the google developers console

11. Now that the OAuth consent screen has been configured you can create an OAuth Client ID. Set the application type to Web application and enter a name for it (e.g. Gmail SMTP App).

12. Copy the Authorized Redirect URL from the settings and paste it into the field here.

screenshot showing how to create a client id by creating a new web app in the google developers console

13. Click Create. This will generate a Client ID and Client Secret for you. Copy and paste them into the settings area of the plugin.

14. Configure the rest of the settings. It includes,

OAuth Email Address: The email address that you will use for SMTP authentication. This should be the same email used in the Google Developers Console.

From Email Address: The email address which will be used as the From Address when sending an email.

From Name: The name which will be used as the From Name when sending an email.

Type of Encryption: The encryption which will be used when sending an email (either TLS/SSL). By default, it should be set to TLS since SSL has been deprecated since 1998.

SMTP Port: The port which will be used when sending an email. If you choose TLS it should be set to 587. For SSL use port 465 instead.

15. Click Save Changes.

Now that you have configured the settings a Grant Permission button will appear.

screenshot showing how to grant permission from the gmail smtp settings

16. Clicking on it will take you to a consent screen where you will be able to grant this app access to the Gmail API.

allow application screen of google developers console

17. When you click Allow you will get redirected back to the plugin settings. You should see a message like Access Granted Successfully. The SMTP Status should also get set from Not Connected to Connected.

screenshot of gmail smtp settings

That’s it. Gmail SMTP plugin will now be able to take control of all outgoing email from your website.

Test Email

In order to test the email functionality, you can send a test email from the Test Email tab.

Debug option is enabled by default for the test email functionality – which means you would be able to see if the plugin was able to send the email without any error.

screenshot showing how to send a test email from the gmail smtp plugin settings


By default, your SMTP port should be configured on 587 (with TLS encryption). If you can’t get it to work then you can try changing it to 465 (with SSL encryption).

If you still can’t get either to work try port 25 with TLS first and then SSL. Please note that most servers don’t support encryption on port 25, which is why port 587 and 465 are the preferred options.

smtp connect() failed

If you are connecting to the Gmail SMTP server for the first, you might get an error: smtp connect() failed or Could not authenticate.

This error usually occurs when Gmail blocks an SMTP connection made from an external server. This is not a configuration issue. Gmail does it time to time for security reasons. In order to fix this issue login to your Gmail account first. You should see a security warning from Gmail upon login – “Your account has been hacked” or “Somebody stole your password”. As soon as you confirm that it was you who tried to log in (Just click on the link that shows up in that message), the plugin should be able to connect to the Gmail SMTP server.

Error Invalid Scope

Google recently enhanced their risk assessment for new web applications that request user data. Based on this risk assessment, some web applications will require a manual review before users can approve data permissions. Until the review is complete, unverified apps will display an “invalid_scope” or some other random error messages when you go to the permissions consent page.

If you are getting this type of error when setting up the plugin you can join this Google group Risky Access Permissions By Unreviewed Apps. This will automatically approve data access to the app from your account and you won’t have to go through their manual review process (which includes filling out a developer verification form). This automatic approval process is permissible by Google for testing/personal use/sending email through WordPress Plugins/similar single-account SMTP usage (See this page for more details).

Error refreshing the OAuth2 token

This is an intermittent issue that seems to occur on some servers. When you get this error, it means that the plugin is not being able to refresh the OAuth2 token using the secret access key. It is required by the App that you created in your account to access the Gmail API. Usually, the issue goes away when you delete the existing secret access key from the database and do a fresh authorization. For details please check the “Fresh Authorization” section.

OpenSSL Certificate Verification Failure

As of PHP 5.6, you will get the following error/warning if the SSL certificate on the server is not properly configured:

Warning: stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

In order to fix this issue, your web host needs to replace this invalid, misconfigured or self-signed certificate with a good one. The other alternative is to check this option in the settings so PHP doesn’t verify the certificate – “Disable SSL Certificate Verification”. That said, I wouldn’t recommend it since this change was made for a good reason.

Fresh Authorization / Removing Access From the Application

For some reason, if you ever want to stop using this plugin or do a fresh authorization this option might come in handy.

Revoke Access menu allows you to remove access from a previously authorized application.

screenshot showing the revoke access settings of gmail smtp plugin

First, you need to click on the account settings link. This will take you to a page where you can remove access from the Gmail SMTP application.

screenshot showing how to remove access from an application in the google developers console

Once you have removed access from it, go back to the Remove Access tab in the plugin settings and delete the Access key.

Access key is a token received by the plugin when you first granted your app access to the Gmail API. This token is needed to communicate with the Gmail API and send an email. In order to avoid any confusion, the plugin does not show it on the settings page.

Once this token is deleted the plugin can no longer connect to the Gmail SMTP server or send an email. This means you will need to reauthorize (using the web application link in the settings) before you can start using the plugin again. However, you won’t need to set up everything from scratch as long as the project still exists in your Google Developers Console.

If you have any questions feel free to share it in the comment section.

If you like Gmail SMTP please leave it a rating. A huge thanks in advance!
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257 thoughts on “Gmail SMTP Plugin for WordPress”

  1. Hello Admin,

    Great plugin Thank you..

    Question: When someones uses my form to send me emails I get the email but when I try to reply to it.. its from myself email address .. so it repeats my email .. How can I fix this so it shows the other person email address and I can just reply to it?

    Thank you

    1. @Marios, When using SMTP you are basically sending an email from your account to the recipient (Not from the contact form on your server). That’s why Gmail is automatically putting your actual Gmail address as the reply-to email. That same goes for From email address. The plugin does pass this information to Gmail but it simply ignores them for security reasons.

  2. Any thoughts on why this is failing? I do get the notification that GMAIL STMP is controlling the email and I should remove it. There was no option to approve.

    Connection: opening to, timeout=300, options=array ( ‘ssl’ => array ( ‘verify_peer’ => false, ‘verify_peer_name’ => false, ‘allow_self_signed’ => true, ),)
    Connection: Failed to connect to server. Error number 2. “Error notice: stream_socket_client(): unable to connect to (Network is unreachable)
    SMTP ERROR: Failed to connect to server: Network is unreachable (101)
    SMTP connect() failed.

    Servo Info:
    OS: Linux 3.12.74-20170619.148.ELK6.x86_64 #1 SMP Mon Jun 19 19:48:05 CDT 2017 x86_64
    PHP version: 5.6.29
    WordPress version: 4.8.1
    WordPress multisite: No
    openssl: Available
    allow_url_fopen: Enabled
    stream_socket_client: Available
    fsockopen: Available
    cURL: Available
    cURL Version: 7.24.0, OpenSSL/1.0.0


    1. @George, Bluehost may have blocked port 587 on your server. Please contact them to make sure port 587 is open and supports TLS encryption.

      1. I get the same error with port 465 and I have had other smtp plugins that I could get test emails through port 465.


  3. This morning, I got one test email on port 587 through. It took a while, but it came through. All other tests this morning on port 587 and 465 have all had timeout errors. I guess the bluehost site or gmail server is just very slow.


  4. Hello, Gmail SMTP seems to conflict with the Use-Your-Drive plugin, which is using V3 of the google api. Is there any way to get Gmail SMTP to use V3 as well? See this link for more info:


  5. Love you, you helped me solve a problem for my woocommerce sending out automatic email through GSuite! Huge thanks!!!!

    1. What hosting provider are you using – if you don’t mind me asking. I would like to use the same workflow with my wpforms, but 1and1 hosting provider does not play nice with gmail SMTP. Looking to jump ship on 1and1

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