#11780: document that email.encoders throw TypeError on multipart messages.

diff --git a/Doc/library/email.encoders.rst b/Doc/library/email.encoders.rst
index 5421b9f66f3cf040e315324b40f1092f2621582b..3c32c3bb425d7ab3a3c63adcc07818feb77867cb 100644 (file)
--- a/Doc/library/email.encoders.rst
+++ b/Doc/library/email.encoders.rst
@@ -18,6 +18,10 @@ exactly one argument, the message object to encode.  They usually extract the
 payload, encode it, and reset the payload to this newly encoded value.  They
 should also set the :mailheader:`Content-Transfer-Encoding` header as appropriate.
 
+Note that these functions are not meaningful for a multipart message.  They
+must be applied to individual subparts instead, and will throw a
+:exc:`TypeError` if passed a message whose type is multipart.
+
 Here are the encoding functions provided: