--- a/CHANGES.txt	Sun Jul 03 18:54:18 2016 -0400
+++ b/CHANGES.txt	Sun Jul 03 19:29:50 2016 -0400
@@ -124,6 +124,12 @@
   the retire action. Created while implementing fix for
   issue2550831. Requires restore permission in the schema. See
   upgrading.txt for migrating to 1.6.0 for details. (John Rouillard)
+- issue2550751: Email Header Issue. Noel Garces requested the ability
+  to suppress email headers like "x-roundup-issue-files". With Ralf's
+  addition of the Link/Multilink property attribute
+  'msg_header_property' we can do this easily. Setting the
+  'msg_header_property' to the empty string '' (not to None) will
+  suppress the header for that property. (John Rouillard)
 
 Fixed:
 

--- a/doc/customizing.txt	Sun Jul 03 18:54:18 2016 -0400
+++ b/doc/customizing.txt	Sun Jul 03 19:29:50 2016 -0400
@@ -703,8 +703,11 @@
     
         X-Roundup-issue-assigned_to: joe_user
 
-    for issues where joe_user is the username of the person responsible
-    for this issue.
+    for issues where joe_user is the username of the person
+    responsible for this issue.
+
+    If this property is set to the empty string "", it will prevent
+    the header from being generated on outgoing mail.
 
 All Classes automatically have a number of properties by default:
 

--- a/roundup/roundupdb.py	Sun Jul 03 18:54:18 2016 -0400
+++ b/roundup/roundupdb.py	Sun Jul 03 19:29:50 2016 -0400
@@ -562,6 +562,12 @@
                     label = 'name'
                 if prop.msg_header_property in cl.getprops():
                     label = prop.msg_header_property
+                if prop.msg_header_property == "":
+                    # if msg_header_property is set to empty string
+                    # suppress the header entirely. You can't use
+                    # 'msg_header_property == None'. None is the
+                    # default value.
+                    label = None
                 if not label:
                     continue
                 if isinstance(prop, hyperdb.Link):

--- a/test/test_mailgw.py	Sun Jul 03 18:54:18 2016 -0400
+++ b/test/test_mailgw.py	Sun Jul 03 19:29:50 2016 -0400
@@ -3397,6 +3397,62 @@
 _______________________________________________________________________
 ''')
 
+    def testmsgHeaderPropertyEmptyString(self):
+        ''' Test that setting the msg_header_property to an empty string
+        suppresses the X-Roundup-issue-prop header in generated email.
+        '''
+        reference_email = '''FROM: roundup-admin@your.tracker.email.domain.example
+TO: mary@test.test, richard@test.test
+Content-Type: text/plain; charset="utf-8"
+Subject: [issue1] set keyword
+To: mary@test.test, richard@test.test
+From: "Bork, Chef" <issue_tracker@your.tracker.email.domain.example>
+Reply-To: Roundup issue tracker
+ <issue_tracker@your.tracker.email.domain.example>
+MIME-Version: 1.0
+Message-Id: <followup_dummy_id>
+In-Reply-To: <dummy_test_message_id>
+X-Roundup-Name: Roundup issue tracker
+X-Roundup-Loop: hello
+X-Roundup-Issue-Status: chatting
+Content-Transfer-Encoding: quoted-printable
+
+Bork, Chef <chef@bork.bork.bork> added the comment:
+
+Set the Foo and Baz This keywords along with mary for nosy.
+
+----------
+keyword: +Baz This, Foo
+nosy: +mary
+status: unread -> chatting
+title: Testing... -> set keyword
+
+_______________________________________________________________________
+Roundup issue tracker <issue_tracker@your.tracker.email.domain.example>
+<http://tracker.example/cgi-bin/roundup.cgi/bugs/issue1>
+_______________________________________________________________________
+'''        
+        self.db.keyword.create(name='Foo')
+        self.db.keyword.create(name='Bar')
+        self.db.keyword.create(name='Baz This')
+
+        self.db.issue.properties['keyword'].msg_header_property=''
+
+        nodeid1 = self.doNewIssue()
+        nodeid2 = self._handle_mail('''Content-Type: text/plain;
+  charset="iso-8859-1"
+From: "Bork, Chef" <chef@bork.bork.bork>
+To: issue_tracker@your.tracker.email.domain.example
+Message-Id: <followup_dummy_id>
+In-Reply-To: <dummy_test_message_id>
+Subject: [issue1] set keyword [ keyword =+ Foo,Baz This ; nosy =+ mary ]
+
+Set the Foo and Baz This keywords along with mary for nosy.
+''')
+        assert os.path.exists(SENDMAILDEBUG)
+        self.compareMessages(self._get_mail(), reference_email)
+
+
     def testOutlookAttachment(self):
         message = '''X-MimeOLE: Produced By Microsoft Exchange V6.5
 Content-class: urn:content-classes:message