Dear Steven I am not very much experienced but regarding your question i have a solution The problem is arised due distributed denial-of-service attack. 421 Too many concurrent SMTP connections. The mails are send over the servers through port #25 I would like to request SFI server administrator to modify the exim.conf file. Move the port of 25 to port 889 or some other free port. daemon_smtp_ports = 25 : 889 It means it will listen on both ports. Other code further down in the file limits that port to be used only by authenticated senders. But this could be a temporary solutions. Of course if we move exim off port 25 completely we'll solve the problem, but it would be easier to just unplug the server; the effect would be roughly the same . If you block port 25, then no one can send email to the server. The best solution i would like to suggest SFI to hire a email server to handle SMTP connections only and heavily filter email coming in before relaying it to the real mailserver. OR Check out the IP Adress that is trying for a automated and repeated connection to SFD web. Cheers, Manmohan Brahma India