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.

Do you have comments on this Ask the Expert Q&A? Let us know.

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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