Gmail ratcheted up security options for folks wanting to send email using their SMTP options from another program like 3D.  Typical Gmail account settings used in 3D often look something like this:

SMTP Server:
Login Name: This email address is being protected from spambots. You need JavaScript enabled to view it.
Password: yourgmailpassword
Email User Name: Your Name
Return Email Address: This email address is being protected from spambots. You need JavaScript enabled to view it.
Port: 587
Use SSL: Enabled

However even with correct settings, one might get this error returned from the gmail server: 
"The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at"

This means Gmail requires you to do some extra things before they will "allow" you to send email from an outside program through their server.  Here's the steps known to work at this time:

Log into your gmail account on the web at

Click Gear>Settings

Click "Accounts and Import" at the top

Under "Change account settings", choose "Other Google Account settings"

Under Security on the left, scroll down to “Less secure app access" and choose "Turn on access"

When you save your setting and log out of your gmail account, it should now allow third-party apps to be used to send from your account.


Note that if you are using the paid Google Apps for Business, it appears Google Apps has different setup steps than for their free gmail:

  • Re: Gmail 5.5.1 Authentication Required

    by » 2 years ago

    Anecdotally it sounds like Google may again require another "hoop" if you have insecure apps turned on and your gmail suddenly stops sending in 3D.  Users have told us that they went to check the setting in gmail using Googles link/info here -

    And instead of displaying the settings, Google required a "verification" process after which the setting was still on and emailing from 3D worked again.  So you may want to double-check the setting or make sure any verification prompts by Google are completed if you have an issue where it just stops working.

    Also double check that you haven't changed your login password and forgot- if so, update that in 3D also as that may be a quick fix for something simple like that.

  • Re: Gmail 5.5.1 Authentication Required

    by » one year ago

    TWO STEP VERIFICATION: Note that for increased security your Google account may be using 2-factor authentication, also known as 2-step verification. When enabled, they require App Passwords to be used to send emails from third party apps. An App Password is a 16-digit passcode that gives a non-Google app or device permission to access your Google Account. App Passwords can only be used with accounts that have 2-Step Verification turned on.  You would use your app password INSTEAD of your normal password for Google when you set up your emailing settings.

    Here's Google information about creating an App Password:

    If 2-Step Verification is turned off, then you would need to choose to enable access to allow less secure apps (see prior posts above).  Note that even if you selected this in the past, Google may periodically turn this off if it's not in regular use, or if you accidentally choose a security option presented to you without understanding what it changed.

    If 2-Step Verification is turned on, then the option to allow insecure apps is not available and you would need to create and use an App password instead.

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