diff -r 2ca61e72c995 app/models/mail_handler.rb
--- a/app/models/mail_handler.rb	Mon Jul 30 01:32:31 2012 +0000
+++ b/app/models/mail_handler.rb	Tue Jul 31 15:29:05 2012 -0400
@@ -470,6 +470,13 @@
     if assignee.nil?
       assignee ||= assignable.detect {|a| a.is_a?(Group) && a.name.downcase == keyword}
     end
+    # We're going to do a last-ditch iteration for comined names for an edge-case of spaces in names.
+    if assignee.nil? && keyword.match(/ /)
+      assignee ||= assignable.detect { |a| 
+        a.is_a?(User) && 
+        (a.firstname + ' ' + a.lastname).to_s.downcase == keyword
+      }
+    end
     assignee
   end
 end
diff -r 2ca61e72c995 test/fixtures/mail_handler/ticket_assign_user_with_space_in_name.eml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/fixtures/mail_handler/ticket_assign_user_with_space_in_name.eml	Tue Jul 31 15:29:05 2012 -0400
@@ -0,0 +1,19 @@
+Return-Path: <john.doe@somenet.foo>
+Received: from osiris ([127.0.0.1])
+	by OSIRIS
+	with hMailServer ; Sun, 22 Jun 2008 12:28:07 +0200
+Message-ID: <000501c8d452$a95cd7e0$0a00a8c0@osiris>
+From: "John Doe" <john.doe@somenet.foo>
+To: <redmine@somenet.foo>
+Subject: Ticket by unknown user
+Date: Sun, 22 Jun 2008 12:28:07 +0200
+MIME-Version: 1.0
+Content-Type: text/plain;
+	format=flowed;
+	charset="iso-8859-1";
+	reply-type=original
+Content-Transfer-Encoding: 7bit
+
+This is a ticket submitted by an unknown user.
+
+Assigned to: IS - Operations
\ No newline at end of file
diff -r 2ca61e72c995 test/unit/mail_handler_test.rb
--- a/test/unit/mail_handler_test.rb	Mon Jul 30 01:32:31 2012 +0000
+++ b/test/unit/mail_handler_test.rb	Tue Jul 31 15:29:05 2012 -0400
@@ -397,6 +397,40 @@
       end
     end
   end
+  
+  # Defect #11552, users with additional spaces in their names cannot be assigned to using their full name.
+  def test_assign_to_user_with_space_in_name
+    # Create the reported user "IS - Operations"
+    created_user = User.new(:mail => 'dashtest@somenet.foo',
+      :firstname => 'IS -',
+      :lastname => 'Operations')
+    created_user.login = 'dashtest'
+    created_user.save!
+    
+    # Add user to project.
+    project = Project.find_by_identifier('ecookbook')
+    assert_not_nil project
+    member = Member.create(:project => project, :user =>  created_user, :role_ids => [1, 2])
+    
+    # Confirm the user got added correctly.
+    get_user = User.find_by_login('dashtest')
+    assert_not_nil get_user
+    assert_equal 'IS -', get_user.firstname
+    
+    # Bring in an anonymous e-mail, assigned to IS - Operations.
+    issue = submit_email('ticket_assign_user_with_space_in_name.eml',
+      :allow_override => 'assigned_to',
+      :issue => { :project => 'ecookbook' },
+      :no_permission_check => '1',
+      :unknown_user => 'accept')
+    assert issue.is_a?(Issue)
+    assert !issue.new_record?
+    issue.save!
+    
+    # Reload and check and make sure the user is there.
+    issue.reload
+    assert_equal get_user, issue.assigned_to
+  end  
 
   def test_add_issue_should_send_email_notification
     Setting.notified_events = ['issue_added']