Using Google's Gmail for your Outgoing Mail Server (SMTP)

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This article was developed to describe how to utilize Google's Gmail for your outgoing mail server via SMTP.

Important: Centrex does not support SMTP with O365 any longer. We sent out a deprecation notice about this in Aug/Sept 2022.  Clients must use another provider for sending emails.

When using Google’s Gmail as your outgoing SMTP (simple mail transfer protocol) it may require a few steps to ensure the functionality operates properly with our CRM. Google security protocols include a Two-Step Verification (2FA) when logging into a new device, product, or location, even when 2FA is not enabled. An error message such as the one below may result if further configuration is required. 


This is for use on individual user profiles. It is strongly recommended to not use Google SMTP for senders to be used in e-marketing campaigns.


Bad Credentials

If you received the error message above after entering your Gmail credentials for outgoing mail settings and clicking Test SMTP Settings, Google may be preventing authentication as part of their security protocols. 


In order to fix this, you will need to activate the 2FA and use an APP Password. This message can also be found in your system logs. 

If your SMTP credentials have been successfully authenticated you will see the message below. 



Double-checking your username and password

STEP 1: The first and most important step to troubleshoot your credentials is to double-check that your username and password have been entered correctly. The following steps will require you to make changes to your Gmail configuration that will not work if your username and password are incorrect. 


IMPORTANT:  Steps 2 and 3 should be done together.

Activate 2-Step Verification

STEP 2: We recommend using 2FA even if you are not having issues with your SMTP. This is quickly being adopted and enforced on many platforms. Google is taking steps to eventually enforce 2FA on all business accounts. For more information regarding 2-step authentication visit Google 2-Step Verification.

For information on how to activate 2FA for your Google account go to Protect your account with 2-Step Verification.

Generating App Passwords

STEP 3: Per Google “An App Password is a 16-digit passcode that gives a less secure app or device permission to access your Google Account. App Passwords can only be used with accounts that have 2-Step Verification turned on.” Basically, this acts similarly to how an API Key works. It is a dedicated password to be used in an outside system. If you are using 2FA with your google account, you will need to use an App Password in your outgoing mail server settings. For information on generating an APP Password, visit Sign in using app passwords.



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