How to add gmx.com

GMX.COM:
Username:  your.username@gmx.com
Password:   your.password
Server:        gmx.com
Alias:          Mail/GMX.COM (for grouping acounts in the X-notifier window/side bar)

And choose your additional options for gmx.com:
Notify inbox only - or also notify the to your gmx folders filtered/redirected mail
Include spam - notify spam
Show folders - to show your gmx folders in the X-notifier window/side bar
Open automatically - when mail gets notified by X-notifier

Contributed by jeroen