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	<title>Comments on: SMTP Errors &#8211; 550 vs 450</title>
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	<link>http://systembash.com/content/450-vs-550-smtp-errors/</link>
	<description>Technology and System Administration</description>
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		<title>By: Jean-Luc Bretton</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-40309</link>
		<dc:creator>Jean-Luc Bretton</dc:creator>
		<pubDate>Tue, 20 Apr 2010 03:14:47 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-40309</guid>
		<description>&lt;span class=&quot;topsy_trackback_comment&quot;&gt;&lt;span class=&quot;topsy_twitter_username&quot;&gt;&lt;span class=&quot;topsy_trackback_content&quot;&gt;A great article on how I&#039;m going to reduce spam on my postfix server... http://bit.ly/9LKM9X&lt;/span&gt;&lt;/span&gt;</description>
		<content:encoded><![CDATA[<p><span class="topsy_trackback_comment"><span class="topsy_twitter_username"><span class="topsy_trackback_content">A great article on how I&#39;m going to reduce spam on my postfix server&#8230; <a href="http://bit.ly/9LKM9X" rel="nofollow">http://bit.ly/9LKM9X</a></span></span></span></p>
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		<title>By: Chris Barnes</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-17072</link>
		<dc:creator>Chris Barnes</dc:creator>
		<pubDate>Fri, 19 Sep 2008 14:41:12 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-17072</guid>
		<description>Yet another reason to reply with a 550 instead of a 450 - if a person sends a message to an address with a typo (ie. an invalid domain), they&#039;ll get the bounce immediately if the server is responding w/ a 550; if the mail server is using a 450 it might take 3-5 days for the bounce to go back to the sender (during which time they think the message was delivered).</description>
		<content:encoded><![CDATA[<p>Yet another reason to reply with a 550 instead of a 450 &#8211; if a person sends a message to an address with a typo (ie. an invalid domain), they&#8217;ll get the bounce immediately if the server is responding w/ a 550; if the mail server is using a 450 it might take 3-5 days for the bounce to go back to the sender (during which time they think the message was delivered).</p>
]]></content:encoded>
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		<title>By: Chris Barnes</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-41402</link>
		<dc:creator>Chris Barnes</dc:creator>
		<pubDate>Fri, 19 Sep 2008 14:41:00 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-41402</guid>
		<description>Yet another reason to reply with a 550 instead of a 450 - if a person sends a message to an address with a typo (ie. an invalid domain), they&#039;ll get the bounce immediately if the server is responding w/ a 550; if the mail server is using a 450 it might take 3-5 days for the bounce to go back to the sender (during which time they think the message was delivered).</description>
		<content:encoded><![CDATA[<p>Yet another reason to reply with a 550 instead of a 450 &#8211; if a person sends a message to an address with a typo (ie. an invalid domain), they&#8217;ll get the bounce immediately if the server is responding w/ a 550; if the mail server is using a 450 it might take 3-5 days for the bounce to go back to the sender (during which time they think the message was delivered).</p>
]]></content:encoded>
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	<item>
		<title>By: Irene</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-8373</link>
		<dc:creator>Irene</dc:creator>
		<pubDate>Mon, 21 Apr 2008 01:17:57 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-8373</guid>
		<description>Hi,

I have to admit that I know next to nothing on fixing problems on my computer. The problem I have is when trying to post a comment on a certain blog site, I get the message &quot;The website cannot display HTTP 450 most likely the cause. It goes on to this wesite is under maintance, the website has a program error. 
What you can do is; refresh the page, still doing it.
Go back to previous page. Nothing. 

I can read the blog &amp; there are new comments happining but I can&#039;t without the above message happening. This has gone on for 2 days. I have posted many times before on this site with no problem. No my comments are not offensive &amp; I have not been kicked off. Could this be a virus on that blog? Please advice if you have any info to help fix the problem. Easy steps tp do?

Thanks</description>
		<content:encoded><![CDATA[<p>Hi,</p>
<p>I have to admit that I know next to nothing on fixing problems on my computer. The problem I have is when trying to post a comment on a certain blog site, I get the message &#8220;The website cannot display HTTP 450 most likely the cause. It goes on to this wesite is under maintance, the website has a program error.<br />
What you can do is; refresh the page, still doing it.<br />
Go back to previous page. Nothing. </p>
<p>I can read the blog &amp; there are new comments happining but I can&#8217;t without the above message happening. This has gone on for 2 days. I have posted many times before on this site with no problem. No my comments are not offensive &amp; I have not been kicked off. Could this be a virus on that blog? Please advice if you have any info to help fix the problem. Easy steps tp do?</p>
<p>Thanks</p>
]]></content:encoded>
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		<title>By: Irene</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-41401</link>
		<dc:creator>Irene</dc:creator>
		<pubDate>Mon, 21 Apr 2008 01:17:00 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-41401</guid>
		<description>Hi,

I have to admit that I know next to nothing on fixing problems on my computer. The problem I have is when trying to post a comment on a certain blog site, I get the message &quot;The website cannot display HTTP 450 most likely the cause. It goes on to this wesite is under maintance, the website has a program error. 
What you can do is; refresh the page, still doing it.
Go back to previous page. Nothing. 

I can read the blog &amp; there are new comments happining but I can&#039;t without the above message happening. This has gone on for 2 days. I have posted many times before on this site with no problem. No my comments are not offensive &amp; I have not been kicked off. Could this be a virus on that blog? Please advice if you have any info to help fix the problem. Easy steps tp do?

Thanks</description>
		<content:encoded><![CDATA[<p>Hi,</p>
<p>I have to admit that I know next to nothing on fixing problems on my computer. The problem I have is when trying to post a comment on a certain blog site, I get the message &#8220;The website cannot display HTTP 450 most likely the cause. It goes on to this wesite is under maintance, the website has a program error.<br />
What you can do is; refresh the page, still doing it.<br />
Go back to previous page. Nothing. </p>
<p>I can read the blog &amp; there are new comments happining but I can&#8217;t without the above message happening. This has gone on for 2 days. I have posted many times before on this site with no problem. No my comments are not offensive &amp; I have not been kicked off. Could this be a virus on that blog? Please advice if you have any info to help fix the problem. Easy steps tp do?</p>
<p>Thanks</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Aaron</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-5430</link>
		<dc:creator>Aaron</dc:creator>
		<pubDate>Sat, 05 Jan 2008 04:50:07 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-5430</guid>
		<description>There is a part of me that agrees with this method.  If you are getting a ton of connection attempts, then this will reduce DNS lookups (assuming the previous lookup cache expired) and will prevent excessive RBL lookups.

On the other hand, I prefer to keep using 450 especially as it pertains to spammers.  For zombie machines, this won&#039;t do much other than tie up some more connections in my tarpit.  For improperly confirgured mail servers or servers owned by spammers, this means their queues will fill up.  The more they have in their queue, the less spam they will be able to send and the bigger mail servers they will need to buy.

This also means that if people are trying to send mail to my company from a mis-configured mail server and the mail is legit, then both they and I have more time to work out their misconfiguration (usually FcrDNS) and then the world is better off because less people have to leave their mail servers wide open to receive mail from them.  I for one use some very tough and taboo regex filters to blacklist DSL and Cable modems, so I like to have some room for error.  In fact, I could probably shut off spamassassin and stop checking with the RBL&#039;s and I would still stop about 95% of the spam... so it is nice to keep them retrying just in case one of them happens to just be an ignorant DNS admin.

I do get some joe-jabs from time to time, simply because I have been poisoning spammer databases for about 8 years now and some of the get kindof pissed off about it.  That is another tarpit that they don&#039;t realize they are getting into.  If my mail server starts receiving automated bounces from poorly configured mail server, it then sends a single email to each domains abuse and postmaster explaining them that they are replying to forged emails and that they can simply avoid that (at least as it pertains to my domains and any real domains) by checking SPF records.  The spammers jabs are actually so counter-productive that I have actually helped several hundred small companies and organizations to start publishing SPF because of them.  They simply can&#039;t win. :-)</description>
		<content:encoded><![CDATA[<p>There is a part of me that agrees with this method.  If you are getting a ton of connection attempts, then this will reduce DNS lookups (assuming the previous lookup cache expired) and will prevent excessive RBL lookups.</p>
<p>On the other hand, I prefer to keep using 450 especially as it pertains to spammers.  For zombie machines, this won&#8217;t do much other than tie up some more connections in my tarpit.  For improperly confirgured mail servers or servers owned by spammers, this means their queues will fill up.  The more they have in their queue, the less spam they will be able to send and the bigger mail servers they will need to buy.</p>
<p>This also means that if people are trying to send mail to my company from a mis-configured mail server and the mail is legit, then both they and I have more time to work out their misconfiguration (usually FcrDNS) and then the world is better off because less people have to leave their mail servers wide open to receive mail from them.  I for one use some very tough and taboo regex filters to blacklist DSL and Cable modems, so I like to have some room for error.  In fact, I could probably shut off spamassassin and stop checking with the RBL&#8217;s and I would still stop about 95% of the spam&#8230; so it is nice to keep them retrying just in case one of them happens to just be an ignorant DNS admin.</p>
<p>I do get some joe-jabs from time to time, simply because I have been poisoning spammer databases for about 8 years now and some of the get kindof pissed off about it.  That is another tarpit that they don&#8217;t realize they are getting into.  If my mail server starts receiving automated bounces from poorly configured mail server, it then sends a single email to each domains abuse and postmaster explaining them that they are replying to forged emails and that they can simply avoid that (at least as it pertains to my domains and any real domains) by checking SPF records.  The spammers jabs are actually so counter-productive that I have actually helped several hundred small companies and organizations to start publishing SPF because of them.  They simply can&#8217;t win. :-)</p>
]]></content:encoded>
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	<item>
		<title>By: Aaron</title>
		<link>http://systembash.com/content/450-vs-550-smtp-errors/comment-page-1/#comment-41400</link>
		<dc:creator>Aaron</dc:creator>
		<pubDate>Sat, 05 Jan 2008 04:50:00 +0000</pubDate>
		<guid isPermaLink="false">http://systembash.com/content/450-vs-550-smtp-errors/#comment-41400</guid>
		<description>There is a part of me that agrees with this method.  If you are getting a ton of connection attempts, then this will reduce DNS lookups (assuming the previous lookup cache expired) and will prevent excessive RBL lookups.

On the other hand, I prefer to keep using 450 especially as it pertains to spammers.  For zombie machines, this won&#039;t do much other than tie up some more connections in my tarpit.  For improperly confirgured mail servers or servers owned by spammers, this means their queues will fill up.  The more they have in their queue, the less spam they will be able to send and the bigger mail servers they will need to buy.

This also means that if people are trying to send mail to my company from a mis-configured mail server and the mail is legit, then both they and I have more time to work out their misconfiguration (usually FcrDNS) and then the world is better off because less people have to leave their mail servers wide open to receive mail from them.  I for one use some very tough and taboo regex filters to blacklist DSL and Cable modems, so I like to have some room for error.  In fact, I could probably shut off spamassassin and stop checking with the RBL&#039;s and I would still stop about 95% of the spam... so it is nice to keep them retrying just in case one of them happens to just be an ignorant DNS admin.

I do get some joe-jabs from time to time, simply because I have been poisoning spammer databases for about 8 years now and some of the get kindof pissed off about it.  That is another tarpit that they don&#039;t realize they are getting into.  If my mail server starts receiving automated bounces from poorly configured mail server, it then sends a single email to each domains abuse and postmaster explaining them that they are replying to forged emails and that they can simply avoid that (at least as it pertains to my domains and any real domains) by checking SPF records.  The spammers jabs are actually so counter-productive that I have actually helped several hundred small companies and organizations to start publishing SPF because of them.  They simply can&#039;t win. :-)</description>
		<content:encoded><![CDATA[<p>There is a part of me that agrees with this method.  If you are getting a ton of connection attempts, then this will reduce DNS lookups (assuming the previous lookup cache expired) and will prevent excessive RBL lookups.</p>
<p>On the other hand, I prefer to keep using 450 especially as it pertains to spammers.  For zombie machines, this won&#8217;t do much other than tie up some more connections in my tarpit.  For improperly confirgured mail servers or servers owned by spammers, this means their queues will fill up.  The more they have in their queue, the less spam they will be able to send and the bigger mail servers they will need to buy.</p>
<p>This also means that if people are trying to send mail to my company from a mis-configured mail server and the mail is legit, then both they and I have more time to work out their misconfiguration (usually FcrDNS) and then the world is better off because less people have to leave their mail servers wide open to receive mail from them.  I for one use some very tough and taboo regex filters to blacklist DSL and Cable modems, so I like to have some room for error.  In fact, I could probably shut off spamassassin and stop checking with the RBL&#8217;s and I would still stop about 95% of the spam&#8230; so it is nice to keep them retrying just in case one of them happens to just be an ignorant DNS admin.</p>
<p>I do get some joe-jabs from time to time, simply because I have been poisoning spammer databases for about 8 years now and some of the get kindof pissed off about it.  That is another tarpit that they don&#8217;t realize they are getting into.  If my mail server starts receiving automated bounces from poorly configured mail server, it then sends a single email to each domains abuse and postmaster explaining them that they are replying to forged emails and that they can simply avoid that (at least as it pertains to my domains and any real domains) by checking SPF records.  The spammers jabs are actually so counter-productive that I have actually helped several hundred small companies and organizations to start publishing SPF because of them.  They simply can&#8217;t win. :-)</p>
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