QB Issue Resolution:

I suggest making sure that your Send Forms Preferences has the correct settings for your email. You may also need to set it up again to make sure that it will work properly.

Here’s the link that will guide you on how to set up your email in QB. http://support.quickbooks.intuit.com/support/articles/HOW13776

Also check if you can still log in to your email outside QB using your email password.

Resolution for Issue 'email password will not work' available: Yes (Solved).
Source: Intuit Community forum.

email password will not work: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for correct settings
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Error Recovery for correct settings [Canada]
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