There are a few different options as far as checking your Arx Fidelis E-Mail.

First is using SOGo. This is a more advance option.
Arx Fidelis SOGo

Second is the RoundCube. This is a more basic option.
Arx Fidelis RoundCube

With your Arx Fidelis E-Mail address you have s[am protection using SpamFlare.
Arx Fidelis SpamFlare