Fix header decoding to correctly handle multiple recipients

Author: andrewtimberlake

lib/mail/parsers/rfc_2822.ex

@@ -405,21 +405,6 @@ defmodule Mail.Parsers.RFC2822 do
   defp decode_header_value(_key, %DateTime{} = datetime, _opts),
     do: datetime
 
-  defp decode_header_value("received", value, _opts),
-    do: value
-
-  defp decode_header_value(_key, [value | [param | _params] = params], opts)
-       when is_binary(value) and is_tuple(param) do
-    decoded = parse_encoded_word(value, opts)
-    params = Enum.map(params, fn {param, value} -> {param, parse_encoded_word(value, opts)} end)
-    [decoded | params]
-  end
-
-  defp decode_header_value(_key, {name, email}, opts) do
-    decoded = parse_encoded_word(name, opts)
-    {decoded, email}
-  end
-
   defp decode_header_value(key, addresses, opts)
        when key in ["to", "cc", "from", "reply-to"] and is_list(addresses) do
     addresses =
@@ -435,8 +420,28 @@ defmodule Mail.Parsers.RFC2822 do
     addresses
   end
 
+  defp decode_header_value("from", {_name, _address} = value, opts) do
+    [from] = decode_header_value("from", [value], opts)
+    from
+  end
+
   defp decode_header_value("from", value, _opts), do: value
 
+  defp decode_header_value("received", value, _opts),
+    do: value
+
+  defp decode_header_value(_key, [value | [param | _params] = params], opts)
+       when is_binary(value) and is_tuple(param) do
+    decoded = parse_encoded_word(value, opts)
+    params = Enum.map(params, fn {param, value} -> {param, parse_encoded_word(value, opts)} end)
+    [decoded | params]
+  end
+
+  defp decode_header_value(_key, {name, email}, opts) do
+    decoded = parse_encoded_word(name, opts)
+    {decoded, email}
+  end
+
   defp decode_header_value(_key, value, opts) do
     parse_encoded_word(value, opts)
   end

test/mail/parsers/rfc_2822_test.exs

@@ -192,6 +192,20 @@ defmodule Mail.Parsers.RFC2822Test do
     assert Mail.get_html(message) == html_part2
   end
 
+  test "parses a message with multiple recipients" do
+    # Multiple recipients where some have names can be interpreted as a header value with params if not handled correctly.
+    message =
+      parse_email("""
+      To: [email protected], "John Doe" <[email protected]>, [email protected]
+      """)
+
+    assert message.headers["to"] == [
+             "[email protected]",
+             {"John Doe", "[email protected]"},
+             "[email protected]"
+           ]
+  end
+
   test "to_datetime/1" do
     import Mail.Parsers.RFC2822, only: [to_datetime: 1]