I just received an e-mail with "RE-ACTIVATE YOUR XS4ALL EMAIL ACCOUNT" as the subject, stating that the XS4ALL Message Centre is apparently cleaning house and all unused Webmail accounts will be purged unless you provide XS4ALL with you name, address and password.
Do not reply to this mail in any way!
It's rather stupid to suggest that Webmail accounts will be purged, as you get a Webmail account with every POP-address you create. In other words; they can't change this without changing the mail service as a whole.
The return address is some Live.com address the scammers use to harvest the data.
If you think it's useful, send the message as an attachment (to keep the headers intact!) to the XS4ALL Abuse desk; they will handle accordingly. However, I reckon they will get a truckload of these today.
Cheers, K.