Exchange 2010 or Exchange 2013 or Exchange 2016...provided your teammates use Outlook too. If not they can usually find plugins for their software of choice to connect to the same Exchange server that you do.
Is online/SaaS not a (legal) problem for you? Go for a Office 365 subscription (for you and your team), then Microsoft takes care of the Exchange maintenance for you. T^his maintenance can be a headache at times, especially if you have specific wishes or custom API/COM/REST calls to make to it. Exchange in and by itself is expensive, requires a "beefy" system (depending on the amount of mates) and a Windows Server 2009/2012/2016 license. Also not cheap (depending on the "beef" you put into the system).
Way cheaper option is to give your login/password to your teammates
By data, you mean just messages? Also attachments? Is Outlook a must? Do you wish your teammates to have access to your data inside your team's network, or also outside (web-based/online)? And if online access is desired, do you already have a web-presence?
The previous paragraph is an indicator that you need to provide more of a description to get more precise and useful suggestions. Perhaps SharePoint is what you need, or maybe an open-source groupware solution is actually what you are after. From your description it is very hard to give a non-generic answer.