The receiving machine performed a reverse DNS lookup and it came back with different information. If your server is truly setup right and you aren't hijacking someone else's domain name, you should check your DNS setup and verify that the reverse DNS configuration is correct. --Joe -----Original Message----- From: simon whale [mailto:simon@xxxxxxxxxxxxxx] Sent: Thursday, September 19, 2002 6:06 AM To: [ExchangeList] Subject: [exchangelist] Smtp error messages - what does this one mean http://www.MSExchange.org/ Hi, Does anybody know what the following smtp error message means and how do I fix it. #5.5.0 smtp;553 sorry, envelope sender must have a valid domain name (#5.7.1) Many thanks Simon Whale ----------------------------------------------------------------------- This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify admin@xxxxxxxxxxxxxxx The views expressed in this email are those of the individual and not necessarily those of UK Data IT This footnote also confirms that this email message has been swept by SOPHOS AV for the presence of computer viruses. ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=exchangelist Exchange Newsletters: http://www.msexchange.org/pages/newsletter.asp Exchange FAQ: http://www.msexchange.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ ISA Server Resource Site: http://www.isaserver.org Windows Security Resource Site: http://www.windowsecurity.com/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this MSExchange.org Discussion List as: exchlist@xxxxxxxxxxxxxxxxx To unsubscribe send a blank email to $subst('Email.Unsub')