Another basic thing to look at is if they are using a blackhole list or some other spam filter. Some firewalls will be too aggressive in filtering mail that it considers originating from a spam site.
Bruce Fyfe, Network Engineer Lakeside Industries (www.lakesideind.com) (425) 313-2600 -----Original Message----- From: John P. Hoekstra [mailto:[EMAIL PROTECTED]] Sent: Monday, May 13, 2002 10:48 PM To: MSWinNT Discussions Subject: Low level TCP question Hi! I am having TCP/IP connectivity problems with seemingly random hosts on the internet. However, the same hosts are very reliable in not talking to our system. Unfortunately, some of these hosts belong to clients of ours and we can't send them e-mail! Our system is Windows NT 4.0 SP6 with Exchange Server. The top level protocol is SMTP and the connection is timing out sending the body of the mail message. For the hosts that fail to accept the transmission, the pattern seems to be the same: The preliminaries of the SMTP protocol level always succeeds. Our system sends multiple TCP packets containing the mail message with 1460 data bytes in each packet. The remote host NAKs the first packet, so our system retries 5 times The remote host either does not respond or sends a FINISH packet I have netmon traces if anyone wants to see the gory details. John P. Hoekstra [EMAIL PROTECTED] Macatawa Computer Services, Inc. 68-70 West 8th Street Holland MI 49423-3159 ------ You are subscribed as [EMAIL PROTECTED] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to %%email.unsub%% ------ You are subscribed as [email protected] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED]
