Depends upon who is generating the error. If it is your server, then the client is not authenticating to the server or has a misconfiguration. John Tolmachoff Engineer/Consultant/Owner eServices For You > -----Original Message----- > From: NPerez [mailto:nperez@xxxxxxxxxxxxxxx] > Sent: Monday, February 02, 2004 3:16 PM > To: [ExchangeList] > Subject: [exchangelist] Sending Email Problem > > http://www.MSExchange.org/ > > We have Exchange 2k and running Outlook as our clients. I'm having an > issue where certain emails are being returned. The error reads: "550 5.7.1 > Unable to relay for user@xxxxxxxxxxx" > > Anyone know how to correct this? > > Thx! > > ------------------------------------------------------ > 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 > ------------------------------------------------------ > Other Internet Software Marketing Sites: > Leading Network Software Directory: http://www.serverfiles.com > No.1 ISA Server Resource Site: http://www.isaserver.org > Windows Security Resource Site: http://www.windowsecurity.com/ > Network Security Library: http://www.secinf.net/ > Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com > ------------------------------------------------------