--- a/src/pyams_mail/interfaces/__init__.py	Wed Jun 17 09:57:53 2015 +0200
+++ b/src/pyams_mail/interfaces/__init__.py	Thu Jun 02 15:45:37 2016 +0200
@@ -19,4 +19,13 @@
 
 # import packages
 
-from pyams_mail import _
+
+class IPrincipalMailInfo(Interface):
+    """Principal mail informations interfaces"""
+
+    def get_addresses(self):
+        """Get list of mail addresses matching adapted principal
+
+        As adapted principal can be a group, result should be a list of
+        tuples containing name and address of each target
+        """