Using Mail (OSX Lion) to access Exchange 2010

[Eric R]

I have a Mac Air book and an iMac, both running OS X Lion, and both fully up to date. I got the Mac Air about 9 or 10 months ago, and successfully set up Mail to access my business email Outlook 2010 on an Exchange server 2010 (using Outlook Windows Access, ie instead of identifying my mails server as mail.domain-name.com, I have identified it as owa.domain-name.com, or in my case.co.uk). This has worked successfully since then. Last week I bought an iMac standard loaded with OS X Lion 10.6 which updated to 10.8. I have set Mail up exactly as I have it on the Mac Air Book. All folders except SENT have synched. The most recent message in SENT dates from May 2012. Some messages sent from the iMac appear on the Exchange Server as sent but nothing I have sent whether from the office server, from my office pc or from the Mac Air Book appears in SENT on the iMac. I have deleted the account and set it up again on the iMac, but no good. Any ideas?