Using the Update Task feature from the Task Detail View, you can notify your project manager by e-mail of updates on your progress within a project. This feature is more fully documented in the Viewer user guide.
If the email is not being sent and you are seeing an error, such as "Username and Password not accepted", it could be a security setting with the outgoing email account. The outgoing email account is the From account that is configured in the Viewer Preferences dialog. For Gmail users, you will need to go into your Google account and turn on the option to allow less secure apps. The following link will display the setting for your account:
Also note that the SMTP port number for gmail is 587.