diff --git a/Lib/email/utils.py b/Lib/email/utils.py
index a759d23308d..39c22406078 100644
--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -215,6 +215,12 @@ def parsedate_to_datetime(data):
 
 
 def parseaddr(addr):
+    """
+    Parse addr into its constituent realname and email address parts.
+
+    Return a tuple of realname and email address, unless the parse fails, in
+    which case return a 2-tuple of ('', '').
+    """
     addrs = _AddressList(addr).addresslist
     if not addrs:
         return '', ''