Mail database not updating

After updating to 7.2.34062.0 on 6th December, a number of my files, including mail_data.dat  have ceased to be updated (time stamp and size have remained the same). Other files have been updated. Has there been a change in how the mail data is stored in this version? The file that concerns me the most is mail_dtata.dat stored in Local Folders, as this had grown to over 2GB before the program update.

Thanks

Sid