Today there will be a short downtime of the primary server. I've ordered an upgrade for the server. The memory to be installed today around 23:00 clock. This means then a break-of about 5 minutes. The following services will be at this time only limited or even not available: eMail/IMAP, webhosting, FTP, database, VPN, proxy.
Incoming emails will temporarily received by the backup server. So nothing is lost. In this time mails can not be sent or called.
[Update 23:16] The additional memory is installed and the server is back online completely.