Many programs require you to provide details of a mailserver. You can provide an actual mailserver, possibly from your ISP, but that causes emails to be actually send which you may not want for testing. Here is a simple cross-platform mailserver that you can use to test email sending / receiving of any application.

I use JMailSrv, a small, simple and very capable java based Email Server (SMTP & POP). It allows me to send emails to it without actually routing it. This is ideal for testing. I can also fetch emails from any configured account. It provides a Boss account which receives a copy of any email sent to any configured accounts. It has served me perfectly over the years.

Let me know if you find it useful.