Relaying not allowed - please use SMTP AUTH


  • We use Exchange 2007.  When we send to certain domains (just one or two that I know about), we get an undeliverable back saying something like:  #5.0.0 smtp;550 RCPT TO:<> Relaying not allowed - please use SMTP AUTH>.

    Is this because of a DNS/IP issue or something with the SMTP header?

    I'm just using a Send Connector with Address Space as Type SMTP and Address *.  Under Network I'm just using DNS records to route mail (no TLS).  The Source Server is just my "Default-First-Site-Name" Exchange Server.  I have specified our FQDN for the HELO/EHLO response.

    What am I doing wrong and/or what can I do to make the destination server accept emails from my server?



    Friday, February 20, 2009 7:56 PM


  • Hi,

    This does sound like a problem at the recieving end. Try to talk to the admin there and ask what needs to be done to send mail to them.

    • Proposed as answer by Mike Shen Tuesday, February 24, 2009 5:13 AM
    • Marked as answer by Mike Shen Friday, March 06, 2009 5:07 AM
    Saturday, February 21, 2009 6:40 PM