Mount or Dismount an Exchange Server Mailbox is the frequently performed task so you need a best and shortest way to mount database, so here I am explaining an efficient way to Mount the Database files. Follow the instructions given below.
To make it easy for you, I have given a user guide in the form of screen shot so that you can easily Mount or Dismount Exchange Server Mailboxes.
Step 1 - 4 : Connect to Remote Desktop by providing Credentials, go to Start and click on Exchange Management Console.
Step 2 - 4 :   Expand Microsoft Exchange on Premises >> Organization Configuration and click on Mailbox.
Step 3 - 4 : Select a Dismounted Mailbox, Right Click on that and click on Mount Database or you can click on Click on Mount Database from left section as highlighted.
Step 4 - 4 : you can also dismount the mounted database, just right click on mounted database and click on Dismount Database or click on Dismount Database from left section as highlighted.