sya In future we may want to integrate osticket with our company Active Directory (which some emails are being use by multiple user -- as we understand that osticket is email-web based and email acts as unique identifier). Can this be done?
You can use the Authentication:: LDAP and Active Directory plugin to allow users to authenticate against your AD server. You would not be able to import users from AD... (well you could... but the way it works each user with the same email would have their name over written by the next user with the same email.)
I'm not sure what would happen when people who are using a shared an email address try to log in...
I would think that authentication would likely fail as it will not be able to match the email to the correct person.
The way to fix that would be to give each user their own unique email address.
Giving each user a unique email would of course mean that they likely wouldn't be able to log into the old email address to view old tickets in the system. Unless you setup those old emails as a separate account in osTicket.
There are ways to still use the old email addresses (such as shared mailboxes in M365 or mailing lists, etc).
Honestly, I do not understand why any company has users share email addresses, its a terrible practice.
sya Currently we already have existing user and existing ticket. If it can be integrate, do the existing user and tickets will be removed? and do the existing user will not be duplicate?
The tickets would not be removed from osTicket. They would still be there.
But they would only be accessible by Agents who have access to the department that the ticket is in, or the email address / User that opened the ticket.