After an update from an older version to a MailCheck version 4.5.x
or higher, this function is not automatically available. To activate this
function, you will have to log out and then log in
again all e-mail accounts. Afterwards, the function will be fully available
to you in GMX
MailCheck, move your mouse over an unread email that you want to delete.
A trash symbol appears.
To delete your unread e-mail, click on the trash symbol.