diff --git a/offlineimap/head/offlineimap/folder/IMAP.py b/offlineimap/head/offlineimap/folder/IMAP.py
index 943a2a0..6a4ac0c 100644
--- a/offlineimap/head/offlineimap/folder/IMAP.py
+++ b/offlineimap/head/offlineimap/folder/IMAP.py
@@ -78,9 +78,14 @@ class IMAPFolder(BaseFolder):
             # Discard the message number.
             messagestr = string.split(messagestr, maxsplit = 1)[1]
             options = imaputil.flags2hash(messagestr)
-            uid = long(options['UID'])
-            flags = imaputil.flagsimap2maildir(options['FLAGS'])
-            self.messagelist[uid] = {'uid': uid, 'flags': flags}
+            if not options.has_key('UID'):
+                UIBase.getglobalui().warn('No UID in message with options %s' %\
+                                          str(options),
+                                          minor = 1)
+            else:
+                uid = long(options['UID'])
+                flags = imaputil.flagsimap2maildir(options['FLAGS'])
+                self.messagelist[uid] = {'uid': uid, 'flags': flags}
 
     def getmessagelist(self):
         return self.messagelist
diff --git a/offlineimap/head/offlineimap/ui/Noninteractive.py b/offlineimap/head/offlineimap/ui/Noninteractive.py
index 42e5f9e..65b6937 100644
--- a/offlineimap/head/offlineimap/ui/Noninteractive.py
+++ b/offlineimap/head/offlineimap/ui/Noninteractive.py
@@ -26,8 +26,11 @@ class Basic(UIBase):
     def _msg(s, msg):
         print msg
 
-    def warn(s, msg):
-        sys.stderr.write("WARNING: " + str(msg) + "\n")
+    def warn(s, msg, minor = 0):
+        warntxt = 'WARNING'
+        if minor:
+            warntxt = 'warning'
+        sys.stderr.write(warntxt + ": " + str(msg) + "\n")
 
     def sleep(s, sleepsecs):
         if s.verbose >= 0:
diff --git a/offlineimap/head/offlineimap/ui/Tk.py b/offlineimap/head/offlineimap/ui/Tk.py
index a4b816b..85582b6 100644
--- a/offlineimap/head/offlineimap/ui/Tk.py
+++ b/offlineimap/head/offlineimap/ui/Tk.py
@@ -236,8 +236,12 @@ class VerboseUI(UIBase):
         s.top = None
         TextOKDialog("Main Program Exception", exceptionstr)
 
-    def warn(s, msg):
-        TextOKDialog("OfflineIMAP Warning", msg)
+    def warn(s, msg, minor):
+        if minor:
+            # Just let the default handler catch it
+            UIBase.warn(s, msg, minor)
+        else:
+            TextOKDialog("OfflineIMAP Warning", msg)
 
     def showlicense(s):
         TextOKDialog(version.productname + " License",
diff --git a/offlineimap/head/offlineimap/ui/UIBase.py b/offlineimap/head/offlineimap/ui/UIBase.py
index 43107f8..d9678c4 100644
--- a/offlineimap/head/offlineimap/ui/UIBase.py
+++ b/offlineimap/head/offlineimap/ui/UIBase.py
@@ -44,8 +44,11 @@ class UIBase:
         """Generic tool called when no other works."""
         raise NotImplementedError
 
-    def warn(s, msg):
-        s._msg("WARNING: " + msg)
+    def warn(s, msg, minor = 0):
+        if minor:
+            s._msg("warning: " + msg)
+        else:
+            s._msg("WARNING: " + msg)
 
     def debug(s, debugtype, msg):
         thisthread = threading.currentThread()