diff --git a/mercurial/utils/stringutil.py b/mercurial/utils/stringutil.py
--- a/mercurial/utils/stringutil.py
+++ b/mercurial/utils/stringutil.py
@@ -286,3 +286,25 @@
     If s is not a valid boolean, returns None.
     """
     return _booleans.get(s.lower(), None)
+
+_correctauthorformat = remod.compile(br'^[^<]+\s\<[^<>]+@[^<>]+\>$')
+def isauthorwellformed(author):
+    '''Return True if the author field is well formed
+    (ie "Contributor Name <contrib@email.dom>")
+
+    >>> isauthorwellformed(b'Good Author <good@author.com>')
+    True
+    >>> isauthorwellformed(b'Author <good@author.com>')
+    True
+    >>> isauthorwellformed(b'Bad Author')
+    False
+    >>> isauthorwellformed(b'Bad Author <author@author.com')
+    False
+    >>> isauthorwellformed(b'Bad Author author@author.com')
+    False
+    >>> isauthorwellformed(b'<author@author.com>')
+    False
+    >>> isauthorwellformed(b'Bad Author <author>')
+    False
+    '''
+    return _correctauthorformat.match(author) is not None