[Mailman-Users] emails from mailman rejected with error "reject=550 Relaying denied. IP name possibly forged"

[Abdullah Maskari]

Hi,

I seem to have an issue with my mailhost server randomly rejecting emails from my mailman server whenever they are directed externally.
My current setup is I have a mailman server running mailman and sendmail which sends all emails to my mailhost server also running sendmail. Mailhost passes the emails through mailscanner etc. and then relays them either externally or internally based on the target email. Internal relaying works just fine but external relaying seems to sporadically accept some addresses for delivery and reject others. the choice of addresses it chooses to accept or reject is different for every attempt I am so for example for my first attempt it will forward the email to the first and 3rd external email addresses and reject to forward to the rest and on the 2nd attempt it rejects the the 2nd and 3rd and 4th but sends the emails to the 1st and 5th addresses just fine and so on. My mailman server's logs do not show any errors but my mailhost does.
this is the extract in question from my mailhost server mail log file:
Jul 24 09:08:52 mailhost sm-mta[3296]: s6O88pSr003296: from=<Source-email at external-domain.com>, size=2260, class=0, nrcpts=1, msgid=<cq0nx1du5icvm2eubfc8lvdy.1406189339980 at email.android.com>, proto=ESMTP, daemon=MTA-v4, relay=mail-we0-f174.external-domain.com [74.125.82.174]Jul 24 09:08:52 mailhost sm-mta[3296]: s6O88pSr003296: to=<mailman-list at dmz.on.internal-domain.com>, delay=00:00:00, mailer=esmtp, pri=32260, stat=queuedJul 24 09:08:53 mailhost MailScanner[2909]: New Batch: Scanning 1 messages, 2837 bytesJul 24 09:08:53 mailhost MailScanner[2909]: Virus and Content Scanning: StartingJul 24 09:09:07 mailhost MailScanner[2909]: MCP Checks: StartingJul 24 09:09:07 mailhost MailScanner[2909]: Uninfected: Delivered 1 messagesJul 24 09:09:07 mailhost MailScanner[2909]: Deleted 1 messages from processing-databaseJul 24 09:09:08 mailhost sendmail[3307]: s6O88pSr003296: to=<mailman-list at dmz.on.internal-domain.com>, delay=00:00:16, xdelay=00:00:01, mailer=esmtp, pri=122260, relay=mailman-server.dmz.on.internal-domain.com. [172.16.0.143], dsn=2.0.0, stat=Sent (s6O893Rm003831 Message accepted for delivery)Jul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAL003309: ruleset=check_rcpt, arg1=<target-address at external.domain2.com>, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged), reject=550 5.7.1 <target-address at external.domain2.com>... Relaying denied. IP name possibly forged [mailhost ip address]Jul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAL003309: from=<mailman-list-bounces at dmz.on.internal-domain.com>, size=4645, class=0, nrcpts=0, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAN003309: <mailman-list-bounces at dmz.on.internal-domain.com>... User unknownJul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAN003309: from=<>, size=0, class=0, nrcpts=0, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAP003309: from=<>, size=2657, class=0, nrcpts=1, msgid=<201407240809.s6O89CZP003837 at mailman-server.dmz.on.internal-domain.com>, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:16 mailhost sm-mta[3309]: s6O89FAP003309: to=<support-email at internal-domain.com>, delay=00:00:00, mailer=esmtp, pri=32657, stat=queuedJul 24 09:09:16 mailhost sm-mta[3310]: s6O89FRV003310: from=<mailman-list-bounces at dmz.on.internal-domain.com>, size=4640, class=-30, nrcpts=2, msgid=<cq0nx1du5icvm2eubfc8lvdy.1406189339980 at email.android.com>, proto=ESMTP, daemon=MTA-v4, relay=mailhost.serscis.eu [mailhost ip address]Jul 24 09:09:16 mailhost sm-mta[3310]: s6O89FRV003310: to=<Source-email at external-domain.com>, delay=00:00:00, mailer=esmtp, pri=118640, stat=queuedJul 24 09:09:16 mailhost sm-mta[3310]: s6O89FRV003310: to=<target-address at external.domain.com>, delay=00:00:00, mailer=esmtp, pri=118640, stat=queuedJul 24 09:09:16 mailhost sm-mta[3311]: s6O89Fll003311: ruleset=check_rcpt, arg1=<target-address at external.domain3.com>, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged), reject=550 5.7.1 <target-address at external.domain3.com>... Relaying denied. IP name possibly forged [mailhost ip address]Jul 24 09:09:16 mailhost sm-mta[3311]: s6O89Fll003311: from=<mailman-list-bounces at dmz.on.internal-domain.com>, size=4640, class=-30, nrcpts=1, msgid=<cq0nx1du5icvm2eubfc8lvdy.1406189339980 at email.android.com>, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:16 mailhost sm-mta[3311]: s6O89Fll003311: to=<target-address at internal-domain.com>, delay=00:00:00, mailer=esmtp, pri=88640, stat=queuedJul 24 09:09:17 mailhost sm-mta[3311]: s6O89Fln003311: <mailman-list-bounces at dmz.on.internal-domain.com>... User unknownJul 24 09:09:17 mailhost sm-mta[3311]: s6O89Fln003311: from=<>, size=0, class=0, nrcpts=0, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:17 mailhost sm-mta[3311]: s6O89Flp003311: from=<>, size=2657, class=0, nrcpts=1, msgid=<201407240809.s6O89CZP003841 at mailman-server.dmz.on.internal-domain.com>, proto=ESMTP, daemon=MTA-v4, relay=mailhost.server.in-dmz.on.internal-domain.com [mailhost ip address] (may be forged)Jul 24 09:09:17 mailhost sm-mta[3311]: s6O89Flp003311: to=<support-email at internal-domain.com>, delay=00:00:00, mailer=esmtp, pri=32657, stat=queued



Any help would be appreciated.
ThanksAbZ