[otrs] Question about emails from agents

Hi guys, this is my first email to the list, and i'll really appreciate your help. We've been using OTRS for some time for internal help desk, and i want to know if it's possible to make the system recognize when an email is coming from an agent, so this one doesn't has to login to the system and that way we can answer tickets from our email client. Is that or something similar possible with OTRS? Could you tell me why? We tried some different setups, but any email that's sent to the email address associated to OTRS is recognized as from the customer, no matter which is the sender address. Thanks in advance! Ignacio