To send password reset SMS for mailbox or several mailboxes, login to the MSPControl and click on Mailboxes,
or go to Organizations > Exchange > Mailboxes.
You will see the list of all existing mailboxes. If you have many, it might be a good idea to use Search form in the right to find the one you need. You can choose whether you want to search by Display Name, E-mail Address, Domain Account, Account Number, or Login.
Once you found the mailbox(es) you were looking for, select them by checking the corresponding check-boxes in the left.
Then select Send password reset SMS in the drop-down menu Actions, and click Apply.
You will see a notification Action has been successfully performed.
Note: Make sure those mailboxes have a phone number added in their profiles, and, more importantly, check with your administrator if you have an integration with SMS service.