eM Client has built in Chat service which will allow you to communicate instantly with other users of Jabber/XMPP Chat network as well as many other XMPP compatible networks.
Multichat services such as Slack, MS teams and Rocket.Chat are supported as well.
Follow this link to see how to add your Chat account to eM Client.
Check the Working with Chat page to see the overview of how this section works.
Jabber works in much the same way that Email does. There are hundreds of Jabber servers through which a client program can connect. Each Jabber user has his or her own account with one of many Jabber services. When a message is sent, the message goes from that person's computer to his or her nominated Jabber server. This server then sends the message to the recipient's nominated Jabber server.
This way, the Jabber network can not be "down", whereas if the MSN server goes down for maintenance (as it did when it was discontinued), then all MSN users in the world will be disconnected, if one of the decentralized Jabber server goes down, only the users registered to that server are affected.
XMPP Chat service is fully integrated into its Emailing and Contacts managing modules, which means you easily browse your chat log like you can with Emails, and send emails to your Messaging contacts as easily as you can with your other Email correspondents. Furthermore, the Chat and Email modules share their contacts pool; this way this product can merge your Email contacts with your instant messaging contacts and thereby create a truly integrated contacts roster.