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		<title><![CDATA[iRedMail — Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
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		<description><![CDATA[The most recent posts in Helo command rejected: Host not found 450 4.7.1 - error [FIXED].]]></description>
		<lastBuildDate>Thu, 28 May 2020 13:40:29 +0000</lastBuildDate>
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			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74623.html#p74623</link>
			<description><![CDATA[<div class="quotebox"><cite>ZhangHuangbin wrote:</cite><blockquote><p>- Do not remove rules in smtpd_helo_restrictions.<br />- You can whitelist them in /etc/postfix/helo_access.pcre. Make sure your pcre regular expression is correct.</p><p>For example:<br /></p><div class="quotebox"><blockquote><p>May 26 09:15:02 mx postfix/smtpd[12607]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP <span style="color:red">helo=&lt;mtzsvmsmghml02.corporate.ad&gt;</span></p></blockquote></div><p>You should whitelist its HELO hostname &quot;mtzsvmsmghml02.corporate.ad&quot; like this:<br /></p><div class="codebox"><pre><code>/^mtzsvmsmghml02\.corporate\.ad$/ OK</code></pre></div><p>If you want to whitelist all sub-domains, use this one:<br /></p><div class="codebox"><pre><code>/\.corporate\.ad$/ OK</code></pre></div><p>Note, there&#039;s no &#039;^&#039; to match the beginning of the helo hostname.</p></blockquote></div><p>It worked correctly. Thank you very much</p>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Thu, 28 May 2020 13:40:29 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74623.html#p74623</guid>
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		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74608.html#p74608</link>
			<description><![CDATA[<p>- Do not remove rules in smtpd_helo_restrictions.<br />- You can whitelist them in /etc/postfix/helo_access.pcre. Make sure your pcre regular expression is correct.</p><p>For example:<br /></p><div class="quotebox"><blockquote><p>May 26 09:15:02 mx postfix/smtpd[12607]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP <span style="color:red">helo=&lt;mtzsvmsmghml02.corporate.ad&gt;</span></p></blockquote></div><p>You should whitelist its HELO hostname &quot;mtzsvmsmghml02.corporate.ad&quot; like this:<br /></p><div class="codebox"><pre><code>/^mtzsvmsmghml02\.corporate\.ad$/ OK</code></pre></div><p>If you want to whitelist all sub-domains, use this one:<br /></p><div class="codebox"><pre><code>/\.corporate\.ad$/ OK</code></pre></div><p>Note, there&#039;s no &#039;^&#039; to match the beginning of the helo hostname.</p>]]></description>
			<author><![CDATA[null@example.com (ZhangHuangbin)]]></author>
			<pubDate>Thu, 28 May 2020 04:28:21 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74608.html#p74608</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74592.html#p74592</link>
			<description><![CDATA[<p>is it safe and appropriate to leave these options disabled?<br />reject_non_fqdn_helo_hostname<br />reject_unknown_helo_hostname</p>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Wed, 27 May 2020 18:49:10 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74592.html#p74592</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74578.html#p74578</link>
			<description><![CDATA[<p>I commented the lines:<br />reject_non_fqdn_helo_hostname <br />reject_unknown_helo_hostname</p><p>But it&#039;s not safe to keep it that way.<br />log from a mail:<br /></p><div class="codebox"><pre><code>May 26 16:24:40 mx postfix/cleanup[7054]: 49WkRr3gt7z8NZ: message-id=&lt;002101d63372$ca0630e0$5e1292a0$@martins@friboi.com.br&gt;
May 26 16:24:40 mx postfix/qmgr[2706]: 49WkRr3gt7z8NZ: from=&lt;client01@friboi.com.br&gt;, size=4612, nrcpt=1 (queue active)
May 26 16:24:40 mx postfix/amavis/smtp[7059]: &gt; 127.0.0.1[127.0.0.1]:10024: MAIL FROM:&lt;client01@friboi.com.br&gt; SIZE=4612 BODY=8BITMIME
May 26 16:24:40 mx postfix/amavis/smtp[7059]: &lt; 127.0.0.1[127.0.0.1]:10024: 250 2.1.0 Sender &lt;client01@friboi.com.br&gt; OK
May 26 16:24:41 mx postfix/10025/smtpd[7064]: &lt; ip6-localhost[127.0.0.1]: MAIL FROM:&lt;client01@friboi.com.br&gt; BODY=8BITMIME
May 26 16:24:41 mx postfix/10025/smtpd[7064]: dict_pcre_lookup: /etc/postfix/command_filter.pcre: MAIL FROM:&lt;client01@friboi.com.br&gt; BODY=8BITMIME
May 26 16:24:41 mx postfix/10025/smtpd[7064]: extract_addr: input: &lt;client01@friboi.com.br&gt;
May 26 16:24:41 mx postfix/10025/smtpd[7064]: smtpd_check_addr: addr=client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: send attr address = client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: input attribute value: client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: rewrite_clnt: local: client01@friboi.com.br -&gt; client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: send attr address = client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: input attribute value: friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: input attribute value: client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: resolve_clnt: `&#039; -&gt; `client01@friboi.com.br&#039; -&gt; transp=`smtp&#039; host=`friboi.com.br&#039; rcpt=`client01@friboi.com.br&#039; flags= class=default
May 26 16:24:41 mx postfix/10025/smtpd[7064]: ctable_locate: install entry key ?client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: extract_addr: in: &lt;client01@friboi.com.br&gt;, result: client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: rewrite_clnt: cached: local: client01@friboi.com.br -&gt; client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: send attr sender = client01@friboi.com.br
May 26 16:24:41 mx postfix/10025/smtpd[7064]: resolve_clnt: `client01@friboi.com.br&#039; -&gt; `jeferson@mydomain.com.br&#039; -&gt; transp=`dovecot&#039; host=`mydomain.com.br&#039; rcpt=`jeferson@mydomain.com.br&#039; flags= class=virtual
May 26 16:24:41 mx postfix/10025/smtpd[7064]: ctable_locate: install entry key client01@friboi.com.br?jeferson@mydomain.com.br
May 26 16:24:41 mx postfix/cleanup[7054]: 49WkRs52N1z8VT: message-id=&lt;002101d63372$ca0630e0$5e1292a0$@martins@friboi.com.br&gt;
May 26 16:24:41 mx postfix/qmgr[2706]: 49WkRs52N1z8VT: from=&lt;client01@friboi.com.br&gt;, size=5110, nrcpt=1 (queue active)
May 26 16:24:41 mx amavis[2475]: (02475-18) Passed CLEAN {RelayedInbound}, [191.5.61.83]:43158 [187.123.5.86] &lt;client01@friboi.com.br&gt; -&gt; &lt;jeferson@mydomain.com.br&gt;, Queue-ID: 49WkRr3gt7z8NZ, Message-ID: &lt;002101d63372$ca0630e0$5e1292a0$@martins@friboi.com.br&gt;, mail_id: 4vjvqXnSIEyw, Hits: 1.004, size: 4612, queued_as: 49WkRs52N1z8VT, 1172 ms, Tests: [HTML_MESSAGE=0.001,MSGID_MULTIPLE_AT=1,RCVD_IN_MSPIKE_H3=0.001,RCVD_IN_MSPIKE_WL=0.001,SPF_HELO_NONE=0.001,SPF_PASS=-0.001,URIBL_BLOCKED=0.001]</code></pre></div>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Tue, 26 May 2020 19:33:11 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74578.html#p74578</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74577.html#p74577</link>
			<description><![CDATA[<p>Now are hapening with other&nbsp; server mail.<br /></p><div class="codebox"><pre><code>May 26 09:15:02 mx postfix/smtpd[12607]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 09:15:02 mx postfix/smtpd[12607]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 09:30:01 mx postfix/smtpd[14313]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 09:30:01 mx postfix/smtpd[14313]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 09:31:15 mx amavis[11885]: (11885-12) Passed CLEAN {RelayedInternal}, ORIGINATING LOCAL [177.220.144.179]:7521 [177.220.144.179] &lt;001@mydomain.com.br&gt; -&gt; &lt;client02@friboi.com.br&gt;, Queue-ID: 49WYGk4gSPz19b, Message-ID: &lt;35d26e1f-2d46-2fde-35dc-e43143619e41@mydomain.com.br&gt;, mail_id: J3JzvXGPUc4c, Hits: 1.143, size: 514398, queued_as: 49WYGq0mcZz4lq, dkim_new=dkim:mydomain.com.br, 4329 ms, Tests: [ALL_TRUSTED=-1,HTML_IMAGE_ONLY_12=1.629,HTML_MESSAGE=0.001,NORMAL_HTTP_TO_IP=0.001,NUMERIC_HTTP_ADDR=0.001,SUBJ_ALL_CAPS=0.5,T_REMOTE_IMAGE=0.01,URIBL_BLOCKED=0.001]
May 26 09:31:15 mx postfix/amavis/smtp[14357]: 49WYGk4gSPz19b: to=&lt;client02@friboi.com.br&gt;, relay=127.0.0.1[127.0.0.1]:10026, delay=4.5, delays=0.19/0/0.01/4.3, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 49WYGq0mcZz4lq)
May 26 09:31:15 mx amavis[12764]: (12764-04) Passed CLEAN {RelayedInternal}, ORIGINATING LOCAL [177.220.144.179]:7521 [177.220.144.179] &lt;001@mydomain.com.br&gt; -&gt; &lt;client04s@friboi.com.br&gt;, Queue-ID: 49WYGk4gSPz19b, Message-ID: &lt;35d26e1f-2d46-2fde-35dc-e43143619e41@mydomain.com.br&gt;, mail_id: knHN67bVBVPh, Hits: 1.143, size: 514398, queued_as: 49WYGq1jjjz3xN, dkim_new=dkim:mydomain.com.br, 4460 ms, Tests: [ALL_TRUSTED=-1,HTML_IMAGE_ONLY_12=1.629,HTML_MESSAGE=0.001,NORMAL_HTTP_TO_IP=0.001,NUMERIC_HTTP_ADDR=0.001,SUBJ_ALL_CAPS=0.5,T_REMOTE_IMAGE=0.01,URIBL_BLOCKED=0.001]
May 26 09:31:15 mx postfix/amavis/smtp[14358]: 49WYGk4gSPz19b: to=&lt;client04s@friboi.com.br&gt;, relay=127.0.0.1[127.0.0.1]:10026, delay=4.7, delays=0.19/0/0.02/4.5, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 49WYGq1jjjz3xN)
May 26 09:31:15 mx amavis[12282]: (12282-09) Passed CLEAN {RelayedInternal}, ORIGINATING LOCAL [177.220.144.179]:7521 [177.220.144.179] &lt;001@mydomain.com.br&gt; -&gt; &lt;client05@friboi.com.br&gt;, Queue-ID: 49WYGk4gSPz19b, Message-ID: &lt;35d26e1f-2d46-2fde-35dc-e43143619e41@mydomain.com.br&gt;, mail_id: ZHOJfqXPEfHF, Hits: 1.143, size: 514398, queued_as: 49WYGq368Vz3kM, dkim_new=dkim:mydomain.com.br, 4640 ms, Tests: [ALL_TRUSTED=-1,HTML_IMAGE_ONLY_12=1.629,HTML_MESSAGE=0.001,NORMAL_HTTP_TO_IP=0.001,NUMERIC_HTTP_ADDR=0.001,SUBJ_ALL_CAPS=0.5,T_REMOTE_IMAGE=0.01,URIBL_BLOCKED=0.001]
May 26 09:31:15 mx postfix/amavis/smtp[14360]: 49WYGk4gSPz19b: to=&lt;client05@friboi.com.br&gt;, relay=127.0.0.1[127.0.0.1]:10026, delay=4.9, delays=0.19/0/0.01/4.6, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 49WYGq368Vz3kM)
May 26 09:31:17 mx postfix/smtp[14538]: 49WYGq1jjjz3xN: to=&lt;client04s@friboi.com.br&gt;, relay=burns.jbs.com.br[191.5.61.83]:25, delay=2.4, delays=0.05/0.03/0.6/1.7, dsn=2.0.0, status=sent (250 2.0.0 OK E4/08-07479-31C0DCE5)
May 26 09:31:17 mx postfix/smtp[14539]: 49WYGq368Vz3kM: to=&lt;client05@friboi.com.br&gt;, relay=burns.jbs.com.br[191.5.61.83]:25, delay=2.4, delays=0.03/0.03/0.45/1.9, dsn=2.0.0, status=sent (250 2.0.0 OK 25/08-07479-31C0DCE5)
May 26 09:31:21 mx postfix/smtp[14321]: 49WYGq0mcZz4lq: to=&lt;client02@friboi.com.br&gt;, relay=burns.jbs.com.br[191.5.61.83]:25, delay=6.1, delays=0.04/0.01/0.8/5.2, dsn=2.0.0, status=sent (250 2.0.0 OK 85/08-07479-41C0DCE5)
May 26 10:58:01 mx postfix/smtpd[23046]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 10:58:01 mx postfix/smtpd[23046]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 11:00:02 mx postfix/smtpd[21853]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 11:00:02 mx postfix/smtpd[21853]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 11:28:02 mx postfix/smtpd[25860]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 11:28:02 mx postfix/smtpd[25860]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 12:28:03 mx postfix/smtpd[31608]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 12:28:03 mx postfix/smtpd[31608]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client01@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 12:39:34 mx postfix/smtpd[31800]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client04s@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 12:39:36 mx postfix/smtpd[31800]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client04s@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:41:13 mx postfix/smtpd[2890]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client05@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:02 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;006@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:02 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;006@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:02 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;002@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:02 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;004@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:03 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;001@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:03 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;005@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;
May 26 13:42:03 mx postfix/smtpd[1509]: NOQUEUE: reject: RCPT from burns.jbs.com.br[191.5.61.83]: 450 4.7.1 &lt;mtzsvmsmghml02.corporate.ad&gt;: Helo command rejected: Host not found; from=&lt;client03@friboi.com.br&gt; to=&lt;006@mydomain.com.br&gt; proto=ESMTP helo=&lt;mtzsvmsmghml02.corporate.ad&gt;</code></pre></div>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Tue, 26 May 2020 18:19:29 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74577.html#p74577</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74572.html#p74572</link>
			<description><![CDATA[<p>Output from&nbsp; postconf smtpd_helo_restrictions<br /></p><div class="codebox"><pre><code>smtpd_helo_restrictions = 
permit_mynetworks 
permit_sasl_authenticated 
check_helo_access pcre:/etc/postfix/helo_access.pcre 
reject_non_fqdn_helo_hostname 
reject_unknown_helo_hostname</code></pre></div>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Tue, 26 May 2020 11:30:57 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74572.html#p74572</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74558.html#p74558</link>
			<description><![CDATA[<p>Please show us output of command &quot;postconf smtpd_helo_restrictions&quot;. It should be:<br /></p><div class="codebox"><pre><code>smtpd_helo_restrictions =
    permit_mynetworks
    permit_sasl_authenticated
    check_helo_access pcre:/etc/postfix/helo_access.pcre
    reject_non_fqdn_helo_hostname
    reject_unknown_helo_hostname</code></pre></div><p>Then you can whitelists in /etc/postfix/helo_access.pcre will be applied before (Postfix) checking its reverse domain name (&quot;Host not found&quot;).</p>]]></description>
			<author><![CDATA[null@example.com (ZhangHuangbin)]]></author>
			<pubDate>Tue, 26 May 2020 01:53:16 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74558.html#p74558</guid>
		</item>
		<item>
			<title><![CDATA[Re: Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74551.html#p74551</link>
			<description><![CDATA[<p>Which is the domain that you own and will be receiving email for?</p>]]></description>
			<author><![CDATA[null@example.com (websavages)]]></author>
			<pubDate>Mon, 25 May 2020 20:18:48 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74551.html#p74551</guid>
		</item>
		<item>
			<title><![CDATA[Helo command rejected: Host not found 450 4.7.1 - error [FIXED]]]></title>
			<link>https://forum.iredmail.org/post74544.html#p74544</link>
			<description><![CDATA[<p>==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====<br />- iRedMail version (check /etc/iredmail-release): 1.0<br />- Deployed with iRedMail Easy or the downloadable installer? downloadable <br />- Linux/BSD distribution name and version:&nbsp; Ubuntu 18.04 64<br />- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MariaDB<br />- Web server (Apache or Nginx): Nginx<br />- Manage mail accounts with iRedAdmin-Pro? No<br />- [IMPORTANT] Related original log or error message is required if you&#039;re experiencing an issue.<br />====</p><br /><p>I need help because my email server is blocking messages from some vendors,.<br />mail.log<br /></p><div class="codebox"><pre><code>May 23 10:33:22 mx postfix/smtpd[28516]: connect from smtp08.novapontocom.com.br[177.126.185.182]
May 23 10:33:22 mx postfix/smtpd[28516]: Anonymous TLS connection established from smtp08.novapontocom.com.br[177.126.185.182]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
May 23 10:33:22 mx postfix/smtpd[28516]: NOQUEUE: reject: RCPT from smtp08.novapontocom.com.br[177.126.185.182]: 450 4.7.1 &lt;SMTP-MX-4.dc.nova&gt;: Helo command rejected: Host not found; from=&lt;falecom@sac.extra.com.br&gt; to=&lt;user@mydomain.com.br&gt; proto=ESMTP helo=&lt;SMTP-MX-4.dc.nova&gt;
May 23 10:33:22 mx postfix/smtpd[28516]: disconnect from smtp08.novapontocom.com.br[177.126.185.182] ehlo=2 starttls=1 mail=1 rcpt=0/1 data=0/1 rset=1 quit=1 commands=6/8

May 23 11:42:49 mx postfix/smtpd[3300]: connect from smtp07.novapontocom.com.br[177.126.185.96]
May 23 11:42:49 mx postfix/smtpd[3300]: Anonymous TLS connection established from smtp07.novapontocom.com.br[177.126.185.96]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
May 23 11:42:49 mx postfix/smtpd[3300]: NOQUEUE: reject: RCPT from smtp07.novapontocom.com.br[177.126.185.96]: 450 4.7.1 &lt;SMTP-MX-3.dc.nova&gt;: Helo command rejected: Host not found; from=&lt;falecom@sac.extra.com.br&gt; to=&lt;user@mydomain.com.br&gt; proto=ESMTP helo=&lt;SMTP-MX-3.dc.nova&gt;
May 23 11:42:49 mx postfix/smtpd[3300]: disconnect from smtp07.novapontocom.com.br[177.126.185.96] ehlo=2 starttls=1 mail=1 rcpt=0/1 data=0/1 rset=1 quit=1 commands=6/8</code></pre></div><p>I tried the following commands:<br /></p><div class="codebox"><pre><code>python  /opt/iredapd/tools/spf_to_greylist_whitelists.py .novapontocom.com.br
python  /opt/iredapd/tools/spf_to_greylist_whitelists.py novapontocom.com.br
python  /opt/iredapd/tools/spf_to_greylist_whitelists.py sac.extra.com.br
python  /opt/iredapd/tools/spf_to_greylist_whitelists.py smtp08.novapontocom.com.br
python  /opt/iredapd/tools/wblist_admin.py --add --whitelist 177.126.185.182
python  /opt/iredapd/tools/spf_to_greylist_whitelists.py falecom@sac.extra.com.br
python  /opt/iredapd/tools/spf_to_greylist_whitelists.py sac.extra.com.br
python /opt/iRedAPD-3.3/tools/greylisting_admin.py --disable --to &#039;@sac.extra.com.br&#039;
python /opt/iredapd/tools/wblist_admin.py --add --whitelist @sac.extra.com.br @extra.com.br @.extra.com.br
python /opt/iRedAPD-3.3/tools/spf_to_greylist_whitelists.py novapontocom.com.br
python /opt/iRedAPD-3.3/tools/spf_to_greylist_whitelists.py extra.com.br
python /opt/iredapd/tools/wblist_admin.py --add --whitelist @.novapontocom.com.br</code></pre></div><p>And added on end of /etc/postfix/helo_access.pcre:<br />/^.novapontocom\.com\.br$/ OK<br />/^sac\.extra\.com\.br$/ OK<br />/\.novapontocom\.com\.br$/ OK<br />/\.extra\.com\.br$/ OK</p><br /><p>I restarted the services and the server, but it didn&#039;t work.<br />I have no idea what I could do, could anyone help?</p>]]></description>
			<author><![CDATA[null@example.com (RafaelMass)]]></author>
			<pubDate>Mon, 25 May 2020 19:01:06 +0000</pubDate>
			<guid>https://forum.iredmail.org/post74544.html#p74544</guid>
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