This is an example patch which is corrupted when saved using Thunderbird
v2.0.0.19.
---
diff --git a/autoconf.m4f b/autoconf.m4f
new file mode 100644
index 0000000..73283b5
--- /dev/null
+++ b/autoconf.m4f
@@ -0,0 +1,6 @@
+T31,23
+m4_location(_AC_LIST_MEMBER_IF)autoconf/fortran.m4:115
+T17,203
+m4_cr_not_Letters
+
!"#$%&'()*+,./0123456789:;<=>?@[\]^_`{|}~