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sender_email - email address that does not exist, but must be used as FROM address, because receiver host rejects emails from other emails.

receiver_email - email that is supposed to receive the sent message

local_smtp - SMTP server that is installed on another computer in the local network and forwards all received messages to external_smtp

external_smtp - SMTP server that is installed on a computer in another network and rejects all emails that do not come from sender_email

I have configured sendmail to send emails from sender_email and authenticate with user/password to local_smtp that is supposed to send the email message further to external_smtp that only accepts emails sent from a specific email, which is sender_email in this case. However, judging from the log files sendmail authenticates with external_smtp instead of local_smtp. I do not want to authenticate with external_smtp, because that is up to local_smtp.

logfile:

10745 <<< Subject: Terminal Email Send 10745 <<< 10745 <<< Email Content line 1 10745 <<< Email Content line 2 10745 <<< [EOF] 10759 === CONNECT local_smtp. 10759 <<< 220 **********************************************************************^M 10759 >>> EHLO mgmt-snmp 10759 <<< 250-local_smtp says hello^M 10759 <<< 250-AUTH LOGIN PLAIN^M 10759 <<< 250-VRFY^M 10759 <<< 250 8BITMIME^M 10759 >>> MAIL From:<sender_email> AUTH=sender_email 10759 <<< 530 authentication required^M 10759 >>> This is a MIME-encapsulated message 10759 >>> 10759 >>> --t8IEdmbX010759.1442587188/mgmt-snmp 10759 >>> 10759 >>> The original message was received at Fri, 18 Sep 2015 16:39:48 +0200 10759 >>> from root@localhost 10759 >>> 10759 >>> ----- The following addresses had permanent fatal errors ----- 10759 >>> receiver_email 10759 >>> (reason: 530 authentication required) 10759 >>>

I guess it has something to do with AUTH=sender_email, but I do not know how to change it.

sendmail.mc:

divert(-1)dnl #----------------------------------------------------------------------------- # $Sendmail: debproto.mc,v 8.14.4 2014-02-11 13:02:08 cowboy Exp $ # # Copyright (c) 1998-2010 Richard Nelson. All Rights Reserved. # # cf/debian/sendmail.mc. Generated from sendmail.mc.in by configure. # # sendmail.mc prototype config file for building Sendmail 8.14.4 # # Note: the .in file supports 8.7.6 - 9.0.0, but the generated # file is customized to the version noted above. # # This file is used to configure Sendmail for use with Debian systems. # # If you modify this file, you will have to regenerate /etc/mail/sendmail.cf # by running this file through the m4 preprocessor via one of the following: # * make (or make -C /etc/mail) # * sendmailconfig # * m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf # The first two options are preferred as they will also update other files # that depend upon the contents of this file. # # The best documentation for this .mc file is: # /usr/share/doc/sendmail-doc/cf.README.gz # #----------------------------------------------------------------------------- divert(0)dnl # # Copyright (c) 1998-2005 Richard Nelson. All Rights Reserved. # # This file is used to configure Sendmail for use with Debian systems. # define(`_USE_ETC_MAIL_')dnl include(`/usr/share/sendmail/cf/m4/cf.m4')dnl VERSIONID(`$Id: sendmail.mc, v 8.14.4-4.1ubuntu1 2014-02-11 13:02:08 cowboy Exp $') OSTYPE(`debian')dnl DOMAIN(`debian-mta')dnl dnl # Items controlled by /etc/mail/sendmail.conf - DO NOT TOUCH HERE undefine(`confHOST_STATUS_DIRECTORY')dnl #DAEMON_HOSTSTATS= dnl # Items controlled by /etc/mail/sendmail.conf - DO NOT TOUCH HERE dnl # dnl # General defines dnl # dnl # SAFE_FILE_ENV: [undefined] If set, sendmail will do a chroot() dnl # into this directory before writing files. dnl # If *all* your user accounts are under /home then use that dnl # instead - it will prevent any writes outside of /home ! dnl # define(`confSAFE_FILE_ENV', `')dnl dnl # dnl # Daemon options - restrict to servicing LOCALHOST ONLY !!! dnl # Remove `, Addr=' clauses to receive from any interface dnl # If you want to support IPv6, switch the commented/uncommentd lines dnl # FEATURE(`no_default_msa')dnl dnl DAEMON_OPTIONS(`Family=inet6, Name=MTA-v6, Port=smtp, Addr=::1')dnl DAEMON_OPTIONS(`Family=inet, Name=MTA-v4, Port=smtp')dnl dnl DAEMON_OPTIONS(`Family=inet6, Name=MSP-v6, Port=submission, M=Ea, Addr=::1')dnl DAEMON_OPTIONS(`Family=inet, Name=MSP-v4, Port=submission, M=Ea, Addr=127.0.0.1')dnl dnl # dnl # Be somewhat anal in what we allow define(`confPRIVACY_FLAGS',dnl `needmailhelo,needexpnhelo,needvrfyhelo,restrictqrun,restrictexpand,nobodyreturn,authwarnings')dnl dnl # dnl # Define connection throttling and window length define(`confCONNECTION_RATE_THROTTLE', `15')dnl define(`confCONNECTION_RATE_WINDOW_SIZE',`10m')dnl dnl # dnl # Features dnl # dnl # use /etc/mail/local-host-names FEATURE(`use_cw_file')dnl dnl # dnl # The access db is the basis for most of sendmail's checking FEATURE(`access_db', , `skip')dnl dnl # dnl # The greet_pause feature stops some automail bots - but check the dnl # provided access db for details on excluding localhosts... FEATURE(`greet_pause', `1000')dnl 1 seconds dnl # dnl # Delay_checks allows sender<->recipient checking FEATURE(`delay_checks', `friend', `n')dnl dnl # dnl # If we get too many bad recipients, slow things down... define(`confBAD_RCPT_THROTTLE',`3')dnl dnl # dnl # Stop connections that overflow our concurrent and time connection rates FEATURE(`conncontrol', `nodelay', `terminate')dnl FEATURE(`ratecontrol', `nodelay', `terminate')dnl dnl # dnl # If you're on a dialup link, you should enable this - so sendmail dnl # will not bring up the link (it will queue mail for later) dnl define(`confCON_EXPENSIVE',`True')dnl dnl # dnl # Dialup/LAN connection overrides dnl # include(`/etc/mail/m4/dialup.m4')dnl include(`/etc/mail/m4/provider.m4')dnl dnl LOCAL_CONFIG dnl EXPOSED_USER(root uucp)dnl # users exempt from masquerading dnl LOCAL_USER(root)dnl dnl MASQUERADE_AS(`external_smtp')dnl dnl FEATURE(`allmasquerade')dnl dnl FEATURE(`masquerade_envelope')dnl dnl FEATURE(`nullclient', local_smtp)dnl LOCAL_CONFIG ## Custom configurations below (will be preserved) define(`SMART_HOST', `local_smtp')dnl define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl FEATURE(`authinfo', `hash /etc/mail/authinfo')dnl define(`RELAY_MAILER_ARGS', `TCP $h 25')dnl dnl # dnl # Default Mailer setup MAILER_DEFINITIONS MAILER(`local')dnl MAILER(`smtp')dnl

authinfo:

AuthInfo:local_smtp "U:root" "I:my_username" "P:my_password"
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4
  • 1
    Looks like whatever is connecting to local_smtp is not authenticating, as it did not issue an AUTH verb, and instead issued a MAIL FROM, which local_smtp then shot down. Is the MTA on whatever is connecting to local_smtp properly configured to authenticate as a client? Commented Sep 18, 2015 at 15:49
  • I use sendmail for authentication and it is configured in sendmail.mc file: FEATURE(``authinfo', ``hash /etc/mail/authinfo')dnl Commented Sep 18, 2015 at 16:24
  • But it did use AUTH for local_smtp: 10759 <<< 250-AUTH LOGIN PLAIN^M. Or is this not it? Commented Sep 21, 2015 at 7:43
  • 1
    That's the banner from the server. Had the client authenticated, I would expect to see a response >>> AUTH .... Instead, there is a >>> MAIL ... line. Commented Sep 21, 2015 at 14:27

1 Answer 1

Reset to default
0

As root send a test message with tracking map (authinfo) lookups.

#!/bin/sh # -d60.5 turn on traking map lookups /usr/sbin/sendmail -d60.5 -v -i -fsender_email -- receiver_email <<END subject: test test END

Possible outcomes to define next tests:

  • no authinfo lookups
  • authinfo lookups with keys other than you expected
  • authinfo lookups returning "no match"
  • authinfo lookups returning correct values
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