Bopup Messenger is a nicely-done instant messaging software that's secure. Security is important especially in a business situation. Bopup Messenger lets users communicate securely across a local area network (LAN) and gives them some nice features to pick from. I like the fact that the software lets you have groups so users within a "team" can communicate with each other.

Bopup Communication Server is a secure messaging suite designed to provide efficient and private communication over networks of any size. The server meets most of the critical business needs, such as centralized management, the Active Directory (LDAP) support, message logging. It can be easily deployed over the business infrastructure to unite the entire companys offices and other locations into one internal IM workspace with control over messaging groups, user permissions to view others and send messages, a message archive with printing support.
Since the server stores and delivers offline messages, users never lose information they are supposed to receive. Messaging is encrypted with powerful algorithms so personal and group conversations are safe and secure even if messages are sent via the Internet. Users can send messages with formatted text, links and graphic emoticons (smileys), organize their personal Contact Lists, access their contacts from any workplace and see who is online and available for communication.
The client program can be configured on the server to run in the Confirmation Mode, which means that the client pops up every time a new message is received and keeps the window on top until the user confirms the message.
To crown it all, Bopup Communication Server is fast to deploy and easy-to-use. It has a outstanding and flexible user interface and comes with a built-in messaging system for scheduled and planned user notifications. Client instant messengers can be easily installed and distributed via Group Policies with the support of pre-installed settings.

The license of this software is Free Trial Software, the price is $219.00, you can free download and get a free trial.