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550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com

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550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com - 17.Oct.2006 5:55:27 PM

alexdcosta

Posts: 28
Joined: 1.Sep.2005
From: Kuwait
Status: offline

Hi all,
I cannot send mails to external domains from my Exchange 2003 SP1 server. I can send/receive mails successfully internally. I get the error:
550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com
Pls. help
Alex

Post #: 1

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RE: 550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com - 17.Oct.2006 6:40:01 PM

jchong

Posts: 2516
Joined: 1.Dec.2005
From: Centreville, Virginia
Status: offline

You can't send to any external domains or just certain ones? Enter your domain name in dnsreport.com and report any errors that it gives.

_____________________________

James Chong
MCSE | M+, S+, MCTS, Security+
msexchangetips.blogspot.com

(in reply to alexdcosta)

Post #: 2

RE: 550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com - 17.Oct.2006 7:23:07 PM

alexdcosta

Posts: 28
Joined: 1.Sep.2005
From: Kuwait
Status: offline

Hi ,
I seem to be having a MX record pointing problem. How do i go abt solving it as per the DNSreport log attached.
1)

FAIL
MX is host name, not IP
ERROR: You have one or more MX record(s) that contain an IP address. This is not valid. A fully RFC-compliant mailserver will not be able to send you mail (although some mail servers will, due to the TCP/IP functions that they use). The problem MX records are:
62.215.205.42.

2)

FAIL
Reverse DNS entries for MX records
ERROR: The IP of one or more of your mail server(s) have no reverse DNS (PTR) entries (if you see "Timeout" below, it may mean that your DNS servers did not respond fast enough). RFC1912 2.1 says you should have a reverse DNS for all your mail servers. It is strongly urged that you have them, as many mailservers will not accept mail from mailservers with no reverse DNS entry. You can double-check using the 'Reverse DNS Lookup' tool at the DNSstuff site (it contacts your servers in real time; the reverse DNS lookups in the DNS report use our local caching DNS server). The problem MX records are:
42.205.215.62.in-addr.arpa [No reverse DNS entry (rcode: 3 ancount: 0) (check it)]

I am currently using DNS services from an oustide provider & using their name servers for mails hosted on our owned server.

Alex

(in reply to jchong)

Post #: 3

RE: 550.5.7.1 UNABLE TO RELAY FOR DOMAIN xxxx@yahoo.com - 18.Oct.2006 10:28:40 AM

uemurad

Posts: 8232
Joined: 7.Jan.2004
From: California, USA
Status: offline

Talk to your DNS hosting service. Ask them to create a PTR record for your address. What this will do is respond with your domain name. Many mail systems use this to verify that messages are coming from legitimate (identifiable) senders by comparing that response to the sending address. This is a step to cut down on spam and without it some systems will reject your messages.

_____________________________

Regards,

Dean T. Uemura
Microsoft MVP - Exchange (2007-2011)
exchangeguy.blogspot.com
uemurad@yahoo.com

(in reply to alexdcosta)

Post #: 4