contact syncing error

For more than a year now I’ve had the below error, which gives me grief when trying to setup groups and sync contacts.  Any ideas on correcting this error?

9:32:50 AM   MailClient.Storage.Application.OperationException: Uploading item(s) to folder ‘jdane@hawkwatch.org/Contacts/’ failed due to the following error: Execution of request failed: https://www.google.com/m8/feeds/contacts/jdane@hawkwatch.org/full/7791f7b50efafa32 ([Line 9, Column 31, element gd:email] g:email/@address is required)