I followed the arrticle here http://support.microsoft.com/kb/912375
to increase my database size limit from 18GB to 25GB. But every night at Exchange database check my information store always dismounts and I get the following error in my even viewer. I tried everything but can't figure out why it keeps happening.
Exchange store 'First Storage Group\Mailbox Store (server)': The current physical size of this database (the .edb file and the .stm file) is 26 GB. This database has exceeded the size limit of 18 GB. However, the logical free space in this database has not yet been evaluated. Therefore, it is possible that this database contains enough free space to bring its logical size below the maximum size limit.
If the logical database size exceeds the maximum size limit, it will be dismounted on a regular basis.