How to authenticate with Google Email Settings API using service account oauth2 Python client?

I'm using Python 2.6 and the client library for Google API which I am trying to use to get authenticated access to email settings :

f = file(SERVICE_ACCOUNT_PKCS12_FILE_PATH, 'rb')
key = f.read()
f.close()
credentials = client.SignedJwtAssertionCredentials(SERVICE_ACCOUNT_EMAIL, key,      scope='https://apps-apis.google.com/a/feeds/emailsettings/2.0/', sub=user_email)

http = httplib2.Http()
http = credentials.authorize(http)
return discovery.build('email-settings', 'v2', http=http)

When I execute this code , I got the follwowing error: UnknownApiNameOrVersion: name: email-settings version: v2

What's the api name and version for email settingsV2? Is it possible to use it with service account? Regards

I found the solution to get email settings using service account oauth2: Here is a example:

  SERVICE_ACCOUNT_EMAIL = ''
  SERVICE_ACCOUNT_PKCS12_FILE_PATH = ''
  EMAIL_SETTING_URI = "https://apps-apis.google.com/a/feeds/emailsettings/2.0/%s/%s/%s" 

 def fctEmailSettings():

    user_email = "user@mail.com"
    f = file(SERVICE_ACCOUNT_PKCS12_FILE_PATH, 'rb')
    key = f.read()
    f.close()
    credentials = client.SignedJwtAssertionCredentials(SERVICE_ACCOUNT_EMAIL, key, scope='https://apps-apis.google.com/a/feeds/emailsettings/2.0/', sub=user_email)
    auth2token = OAuth2TokenFromCredentials(credentials)
    ESclient = EmailSettingsClient(domain='doamin.com')
    auth2token.authorize(ESclient)
    username = 'username'
    setting='forwarding'
    uri = ESclient.MakeEmailSettingsUri(username, setting)
    entry = ESclient.get_entry(uri = uri,  desired_class = GS.gdata.apps.emailsettings.data.EmailSettingsEntry)