Google may block sign-in attempts from some apps or devices that do not use modern security standards. As of October 2015, Google has identified Thunderbird as one of these apps and upon setting up your account, you may receive a "password incorrect" error as a result.
If this is the case, you have two options:
- Use the web version of OCMail to access your email.
- Allow less secure apps to access your account (and thus enable Thunderbird to work properly) by following Google's instructions here.
If you're already familiar with setting up Thunderbird and just want a quick and dirty list of the proper settings, click here.