Hi there ! We have a small business server 2003 for about 2 years with all updates and patches installed. Sometimes an e-mail could not be send andwe get a message like : Final-Recipient: rfc822; receivers e-mail addressAction: delayedStatus: 4.0.0Diagnostic-Code: smtp;421 smtp.1und1.com connection timed outWill-Retry-Until: Mon, 25 Feb 2008 18:02:16 +0100X-Display-Name: name and receivers e-mail address Other users can send an e-mail to the same receiver. On other days the user can send an e-mail without any problems. I have traced the traffic to our e-mail provider with wireshark and found that in such cases the communication to the e-mail provider stops because our server doesn't send the keyword DATA 220 smtp.1und1.com (mrelayeu2) Welcome to Nemesis ESMTP server EHLO xxxxxx_gmbh.de 250-mrelayeu2.kundenserver.de pleased to meet you 250-STARTTLS 250-AUTH PLAIN LOGIN 250-AUTH=PLAIN LOGIN 250-PIPELINING 250-SIZE 52428800 250 HELP AUTH LOGIN YmFydGFsaXNAZGVpbmluZ2VyLWdtYmguZGU= 334 UGFzc3dvcmQ6 ZXJhc2VyMTU= 235 authentication finished successfully MAIL FROM:<e-mail address sender> SIZE=7486 250 mail from: <e-mail address sender> ok RCPT TO:<e-mail address receiver> 250 <e-mail address receiver> ok 421 smtp.1und1.com connection timed out Has anyone an idea what could be the reason for that ? Regards Joachim

Hi Joachim, unfortunately I do not have a solution to that problem. But I want to state out that we have exactly the same problemsfor a few days. We are running a Windows 2003 server and an ExchangeServer 2003. The 1und1 support told us to define the smtp relay as smtp.1und1.de and not smtp.1und1.com - but that doesn't change anything. So I am very interested if there is someody out there who know how to solve the problem. Regards Peter