smtpd banner with wrong hostname

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fferraro87
Posts: 7
Joined: 22 Nov 2017 11:30

smtpd banner with wrong hostname

Post by fferraro87 » 10 Jan 2018 11:40

Hi,
i've add a domain on efa server, but when i try to send an email from another mail server on the same subnet, i've this error :

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Jan 10 11:58:53 mail05-levita postfix/smtp[5569]: 30E6541E6C55: to=<mariachiara.gentile@3bgroup.it>, relay=mx.3bgroup.it[185.96.217.11]:25, delay=0.37, delays=0.01/0.01/0.22/0.13, dsn=4.7.1, status=deferred (host mx.3bgroup.it[185.96.217.11] said: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [172.16.70.254] (in reply to RCPT TO command))
so i've seen this viewtopic.php?f=5&t=2829&p=11249&hilit= ... ted#p11249.
i've enabled full recursion dns and also put on sender server an entry on /etc/hosts but i've still same problem.
So i've try to contact mx.3bgroup.it by telnet on port 25 and i've this welcome message

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220 lev-mail-01.inlevita.it ESMTP Postfix
that is different to my efa server welcome message that is this

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220 proxy.levita.cloud ESMTP Postfix

185.96.217.11 is my efa server and has a right PTR.
so "Client host rejected" i think that can be caused because of this mismatching of welcome message.
Why i don't have the welcome message of efa server?
Thanks

fferraro87
Posts: 7
Joined: 22 Nov 2017 11:30

Re: smtpd banner with wrong hostname

Post by fferraro87 » 10 Jan 2018 13:45

ok i've try to connect via telnet to mx.3bgroup.it on port 25 from another mail server on the same subnet and the smptd banner is right :

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[root@mail ~]# telnet mx.3bgroup.it 25
Trying 185.96.217.11...
Connected to mx.3bgroup.it.
Escape character is '^]'.
220 proxy.levita.cloud ESMTP Postfix
ehlo sender.it    
250-proxy.levita.cloud
250-PIPELINING
250-SIZE 10240000
250-ETRN
250-STARTTLS
250-AUTH LOGIN PLAIN DIGEST-MD5 CRAM-MD5
250-AUTH=LOGIN PLAIN DIGEST-MD5 CRAM-MD5
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<admin@sender.it>
250 2.1.0 Ok
rcpt to:<test@3bgroup.it>
450 4.7.1 Client host rejected: cannot find your reverse hostname, [172.16.70.254]
quit
221 2.0.0 Bye
Connection closed by foreign host.
172.16.70.254 is the gateway of server sender. (and this is behind NAT)

henk
Posts: 171
Joined: 14 Dec 2015 22:16
Location: Netherlands
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Re: smtpd banner with wrong hostname

Post by henk » 10 Jan 2018 22:49

can you resolve any (reverse) hostname on this machine? ( use dig or host)

no: fix dns
yes: see https://wiki.centos.org/HowTos/postfix_restrictions

fferraro87
Posts: 7
Joined: 22 Nov 2017 11:30

Re: smtpd banner with wrong hostname

Post by fferraro87 » 11 Jan 2018 08:12

yeah i can resolve any hostname so it isn't dns problem.

ok, i've already see postfix restrictions, i think that the problem is when sender server (zimbra) check the fcrdns, so i've to whitelist this check.
or maybe it's a problem on my efa server? on my postfix config on webmin i've put on my local networks also 185.96.217.0/24 (public subnet) and 172.16.70.0/24 (private subnet)

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