Icq mailing from a chatbot?

Question

Messengers

Maybe someone remembers, or maybe he knows, there used to be chats in ICQ. Modifications of dimax and others. I wonder how these chatbots sent messages? Was a queue created and sent to everyone? It was not in ICQ and there is no method of sending a message to several at once, what does VK have? How then? To each separately? Maybe someone knows the principle of the bots of those times?