diff --git a/serpent/imap/mailbox.py b/serpent/imap/mailbox.py
index da7e4b1..0cc1755 100644
--- a/serpent/imap/mailbox.py
+++ b/serpent/imap/mailbox.py
@@ -1,11 +1,34 @@
 from mailbox import Maildir
+import os
 
 class ExtendedMaildir(Maildir):
-    def set_flags(self, key):
-        pass
+    def set_flags(self, key, flags):
+        sflags = sorted(flags)
+        if sflags == self.get_flags(key): return True
+        subpath = self._lookup(key)
+        info = '2,' + ''.join(sflags)
+        oldpath = os.path.join(self._path, subpath)
+        newsubdir = os.path.split(subpath)[0]
+        newname = key + self.colon + info
+        if 'S' not in sflags and newsubdir == 'new':
+            newsubdir = 'cur'
+        newpath = os.path.join(self._path, newsubdir, newname)
+        if hasattr(os, 'link'):
+            os.link(oldpath, newpath)
+            os.remove(oldpath)
+        else:
+            os.rename(oldpath, newpath)
+        self._toc[key] = os.path.join(newsubdir, newname)
     def get_flags(self, key):
-        pass
-    def add_flag(self):
-        pass
-    def remove_flag(self):
-        pass
\ No newline at end of file
+        subpath = self._lookup(key)
+        _, name = os.path.split(subpath)
+        info = name.split(self.colon)[-1]
+        if info.startswith('2,'):
+            return info[2:]
+        else:
+            return ''
+    def add_flag(self, flag):
+        self.set_flags(''.join(set(self.get_flags()) | set(flag)))
+    def remove_flag(self, flag):
+        if self.get_flags():
+            self.set_flags(''.join(set(self.get_flags()) - set(flag)))
\ No newline at end of file