[Zendesk Support] Can we set the ticket not to automatically assign to the previous agent?

Hi,

We are using Zendesk Support for Email. Here is your scenario,

1) Customer email the business, and one agent gets the ticket and replies

2) The customer replies to the agent's reply, and the ticket is automatically assigned to the previous agent who replied

Is it possible to configure it such that when the customer replies, it would not assign the ticket to any agent? 

Because we have a pool of agents who can help reply.

Thanks,

Sunny