Q

SMTP reverse lookup failure

SearchExchange.com expert David Sengupta helps troubleshoot an SMTP reverse lookup failure.

A user is having problems sending e-mail to recipients she sends to every day. The error is:

User@otherdomain.com on 11/26/2005 1:11 PM. You do not have permission to send to this recipient. For assistance,

contact your system administrator. ... Relaying denied. IP name possibly forged.(xx.xx.xx.xx)>.

Can you help? I have never seen this 'IP name possibly forged' error before.

It sounds like the recipient's SMTP server is doing a reverse lookup on your domain and failing. You should double-check your public DNS record to make sure that the server's PTR (pointer) record has the servername mapped to the server's correct IP address.

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Related information from SearchExchange.com:

  • Tip: End reverse DNS lookups
  • Expert Advice: Problems sending mail from Exchange 2000 to yahoo.com
  • Free Download: Nslookup
  • Reference Center: DNS tips and resources
  • This was first published in January 2006

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