a recent massive spam-attack on my mailserver has put the latter one into denial mode. This means, that internal mails where still processed, sending out mails too, but the mail-server has refused to accept any Internet-inbound mail.
After identifying the 6 IP-Addresses that where mail-flooding my mail-server, my ISP dropped routing from these IP's, and the mail-server could come back to normal operation. Note - the blue color is Rejected mails.