-.SS "Integrity Check"
-If
-.B mhbuild
-is given the
-.B \-check
-switch, then it will also associate
-an integrity check with each \*(lqleaf\*(rq content. This will add a
-Content-MD5 header field to the content, along with the md5 sum of the
-unencoded contents. This may be used by the receiver of the message to
-verify that the contents of the message were not changed in transport.