Keeping your email password secure is essential to protecting your messages, calendars and contacts. How you go about resetting the mailbox password on an Exchange server varies depending on whether you're trying to reset your own password or someone else's. You reset your own password via the Outlook Web Access panel. Only administrators can change the passwords of other users, and Exchange 2013 doesn't give all administrators the right to change the passwords be default. As such, you must assign yourself password management permissions before you can reset another user's mailbox password.
Reset Your Own Password
Open a new browser tab and log in to your Outlook Web Access panel.
Click the "Options" button in the upper-right corner beneath your username and select "Change Your Password."
Enter the new password in the provided field.
Reset Another User's Password
Open the Exchange Admin Center and log in using an account with administrative privileges.
Click "Permissions" in the Features pane on the left of the screen.
Click the "Admin Roles" tab and select "Organization Management."
Click the "+" button under the Roles heading, select "Reset Password," click "Add" and then click "OK" to give yourself administrative privileges to change user passwords.
Return to the home page of the Exchange Admin Center and click "Recipients."
Click the "Mailboxes" tab and select the user whose password you want to reset.
Click "General" on the left of the screen if it is not already selected.
Place a check mark in the "Reset password for this mailbox" check box, enter the new password in the "New Password" and "Confirm Password" fields and click "Save."
Once you change a user's password on the Exchange server, the user must update her password in all of her mail clients. If she receives email on her smartphone and in Outlook on her computer, for example, the password must be updated in both of these locations or the email client will not be able to log into the Exchange server to send and receive messages.
Information in this article applies to Exchange Server 2013. It may differ slightly or significantly with other versions or products.