Open proxies and open relays are a very common source of spam. Yahoo! uses a variety of techniques to detect these, and Yahoo! does not accept SMTP connections from either open relays or open proxies. Your connection may be rejected because the email server that you use for sending email is probably an "open relay" or "open proxy." These types of email servers can easily be tricked into sending large amounts of unsolicited email.

Many email services refuse mail from such servers, until the server has been fixed to stop relaying spam to innocent users.

To correct this problem, you should contact the system administrator of your mail server (usually "postmaster@your-domain.com") and forward them a copy of the bounced email you received. Otherwise, you should call technical support and alert them of the problem.

You can check to see if your mail server is listed on several of the public open relay DNSBLs. Please note that if your server is not listed at this link, it may still be an open proxy or open relay. Abuse.net provides a web-based open relay test. Instructions to close open relays are readily available on the Internet.

Testing triggers

To determine whether an IP address is an open relay or open proxy, a series of tests need to be performed on that IP address. Yahoo! actively performs tests for open relays and open proxies but only after that IP address has been identified as a source of significant suspicious inbound traffic to the Yahoo! network. In other words Yahoo! only makes reactive tests triggered on inbound traffic from that IP address, and pro-active tests are never performed by Yahoo!.

Minimal impact

Yahoo! strives to ensure that any testing performed as a consequence of the inbound traffic triggers have the least impact possible on the tested address.

Retest policy

Once an IP address has been tested, no further tests are performed for at least three days regardless of the outcome of the tests.

Actions based on test results

If an IP address is determined to be an open relay or open proxy, Yahoo! reserves the right to reject all SMTP traffic from that IP address for a minimum period of 60 days.

Source address of tests

All tests run by Yahoo! are run on readily identifiable servers that have forward and reverse DNS entries ending in yahoo.com. Any email addresses and servers used as part of the testing likewise are always identified with yahoo.com DNS entries or yahoo.com email addresses.

How to remove your server

You should check (and secure) your server for open relays (such as http://www.abuse.net/relay.html) and open proxies (such as http://www.unicom.com/sw/pxytest/ -- these may require installing software on servers outside your network for proper testing). After you are reasonably sure your network is secure, please submit your IP addresses to Yahoo! for retesting.

Thank you, indeed I do get a hard reject saying that they are refusing mail from my IP. Only Yahoo is doing this and I am not on any of the major spam lists but someone out their does not like me. I would check out DNSSTUFF, but I would rather not pay them their annual subscription fee (With auto renew) for a one time search; are their any free black list search service out their? Or can some one who does have an account please search DNSSTUFF for me on one of my IP's? (66.193.205.166) 553 Mail from 66.193.205.166 not allowed - [10] -----Original Message----- From: plug-discuss-bounces@lists.plug.phoenix.az.us [mailto:plug-discuss-bounces@lists.plug.phoenix.az.us] On Behalf Of Richard Wilson Sent: Wednesday, March 12, 2008 9:49 PM To: Main PLUG discussion list Cc: Arizona State University Linux Users Group Subject: Re: Need some SMTP troubleshooting help - Please!. You can check your IP address on dnsstuff.com -- one of their services checks to see if you're listed on any of 200+ Antispam services. You can also try a manual session, doing a telnet to a.mx.mail.yahoo.com (or any of their other mail relays -- "dig yahoo.com mx" will give you the list) and seeing what it is they don't like about you (I assume conerstonehome.com in the example that follows): telnet a.mx.mail.yahoo.com 25 (wait for CONNECT msg) HELO mailserver.cornerstonehom.com (wait for 2XX response) MAIL From: <id@cornerstonehome.com> (wait for response) RCPT To: <id@yahoo.com> (wait for response) DATA send something here . QUIT You may get a 4XX ("soft"/temp) or 5xx (Hard) reject on one of the responses that should indicate why they don't like you. HTH, Richard Wilson (yes I have the "privilege" of getting mail addressed to postmaster at too darn many domains...) ------------------------------------------------------------------------ --- On Wed, 2008-03-12 at 19:23 -0700, Bryan O'Neal wrote:

Ok I have a problem in that I am (still) unable to send anything to Yahoo, or any domain who's email is hosted by Yahoo. I don't get a NDR, it is as if I simply can not connect and I get nothing in my logs! I believe it is connection oriented because three boxes (Two exchange domains and one sendmail) with three external IP's have one common point and that is one border router with one T1 connection. But I can not get any response out of Yahoo and I can not give any details because I have never had to trouble shoot down to this level

553 Mail from x.x.x.x not allowed