We are aware of some problems affecting IMAP and POP access to accounts. We are looking in to this and will update this post when we know more. Apologies for the inconvenience.
Update: 08-Jun-2018 00:30 CEST – This issue is now resolved. A problem with a network service was causing high load on one of our authentication servers, and this was preventing access to POP and IMAP services for some customers. Apologies again for the inconvenience.