Exim v4是什么软件？？？

wowkiller2005

用apt工具安装mysql数据库服务器时，连同它一起安装了，这是什么软件？干什么用的？

apzc2529

Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet. It is freely available under the terms of the GNU General Public Licence. In style it is similar to Smail 3, but its facilities are more general. There is a great deal of flexibility in the way mail can be routed, and there are extensive facilities for checking incoming mail. Exim can be installed in place of sendmail, although the configuration of exim is quite different to that of sendmail.
http://www.exim.org/home.html