AddMessageLabels Method
Adds the specified labels to the message specified by MessageSet.
Syntax
gmail.addMessageLabels(labels, [callback])
Callback
The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).
The callback for this method is defined as:
function(err){ }
'err' is the error that occurred. If there was no error, then 'err' is 'null'.
'err' has 2 properties which hold detailed information:
err.code err.message
Remarks
This method adds the specified labels to the message specified by the MessageSet property. The labels parameter should be set to a space separate list of labels. Labels which contain spaces should be surrounded by quotes.