This error is telling us that your Gmail account does not have the correct security permissions set to allow Dr. Dispatch to send emails on your behalf. This is a Gmal requirement, not a Dr. Dispatch issue.
This is fixed by logging into your Gmail account and modifying your account settings. Please refer to the recommended solutions in the links below the snapshot.
Gmail Instructions To Access Your Account
To help keep your account secure, we may block these less secure apps from accessing your account, and you’ll see a “Password incorrect” error when trying to sign in. If this is the case, you have two options:
- Upgrade to a more secure app that uses the most up to date security measures. All Google products, like Gmail, use the latest security measures.
- Go to Allow less secure apps and choose “Allow” to let less secure apps access your Google account. We don't recommend this option because it may make it easier for someone to gain access to your account.
If you’re still having issues accessing your account after trying the options above, please follow the prompt on this screen: https://accounts.google.com/b/0/DisplayUnlockCaptcha