Apple Mail reply arrow not working reliably I'm running Lion, connecting to an Exchange 2010 server. Sent messages are stored locally.  

Once I've replied to a messages in my Inbox, the "replied" arrow appears to the left of the message, as normal.  But when I click on the arrow to see the actual reply it fails roughly 50% of the time. By "fails" I mean that nothing comes up when I click.  A message I sent minutes earlier/later can work just fine.

The reply WAS sent using Apple Mail (not my iPhone) and it IS in my sent mail folder.  I have re-built my Spotlight index.
As far as I know, the issue is that Microsoft doesn't provide the Active Sync API to anything other than mobile devices. This is why using Exchange on Mac is a bit buggy.

I would recommend using Microsoft's own Outlook Web App (OWA) for your Exchange emails. Or installing the actual Outlook program for your computer. Those are what I use. :)

Those are probably your two best options if you need your email to be 100% reliable on your Mac.