[cobalt-users] Qube3 WebMail bounced back from ISP

[Hartwig Otten <hot@xxxxxxxx>]

We (newbie to this kind of bussiness) connected a Qube3 to an ISP
( via ADSL, PPPoE ), who is managing the email-accounts.

Outgoing mail from other machines (pointing to the Qube3 as mail- and
dns-server)
in our LAN is relayed well by the Qube3,
but WebMail from the Qube3 is bounced back.

I assume we have to manage WebMail to send somehow as
user@xxxxxxxxxxx  instead of user@xxxxxxxxxxxxxxxx ,
because the ISP checks for the email-account ( I assume the 'from:'
phrase ).

I tried to fix that by setting the email's server field "Force Sender
Domain"
to '<mydomain>.de' as advised in knowledgebase # 010518-017542.
/etc/mail/sendmail.cf then contains it in the 'DM' option, but has no
effect.
'/etc/init.d/sendmail restart' also doesn't help.
/var/log/maillog still logs return mails with
"from=user@xxxxxxxxxxxxxxx".

Adding the -X option to /etc/mail/sendmail.args shows me no trace with
WebMail at all, but other mail clients.
So, WebMail seems to be another process and  "Force Sender Domain" is
only working for sendmail, but not for WebMail ?
Is there a similar option for WebMail somewhere else ?

The ISP offers another mailserver ( auth.mail.onlinehome.de ),
with some option to authentificate explicitly ( Email-account, password
).
Possibly, this even would be the more flexible method, but :
How to setup this ?
How secure is it ?

Returned mail (WebMail) contains :

  The original message was received ... from httpd@localhost
   ----- The following addresses had permanent fatal errors -----
   someuser@xxxxxxxxxxxxx
   (reason: 550 relaying to someuser@xxxxxxxxxxxxx prohibited by
administor)
   ----- Transcript of session follows -----
   ... while talking to mail.onlinehome.de:   ( ISP's mailserver )
   >>> RCPT To <someuser@xxxxxxxxxxxxx>
   <<< 550 relaying to someuser@xxxxxxxxxxxxx prohibited by administor
   550 5.1.1 someuser@xxxxxxxxxxxxxxxx User unknown

/var/log/maillog contains :

Jan 23 17:54:43 www sendmail[22370]: g0NGshX22370:
   from=user@xxxxxxxxxxxxxxx, size=250, class=0, nrcpts=1,
   msgid=<200201231654.g0NGshX22370@xxxxxxxxxxxxxxx>,
   proto=SMTP, relay=httpd@localhost
Jan 23 17:54:43 www imapd[22373]: imap service init from
<local-Qube3-IP>
Jan 23 17:54:43 www sendmail[22370]: NOQUEUE: SYSERR: putoutmsg
(localhost):
   error on output channel sending
   "250 2.0.0 g0NGshX22370 Message accepted for delivery": Broken pipe
Jan 23 17:54:43 www sendmail[22375]: g0NGshX22370:
   to=someuser@xxxxxxxxxxxxx,
   ctladdr=user@xxxxxxxxxxxxxxx (504/100),
   delay=00:00:00, xdelay=00:00:00, mailer=relay,
   pri=30250, relay=mail.onlinehome.de [212.227.126.161], dsn=5.1.1,
   stat=User unknown
Jan 23 17:54:43 www sendmail[22375]: g0NGshX22370:
   g0NGshX22375: DSN: User unknown
Jan 23 17:54:44 www sendmail[22375]: g0NGshX22375:
   to=user@xxxxxxxxxxxxxxx,
   delay=00:00:01, xdelay=00:00:01, mailer=local, pri=30350, dsn=2.0.0,
stat=Sent

/etc/named/db.mydomain.de contains :

$TTL 86400
mydomain.de. IN SOA www.mydomain.de. admin.www.mydomain.de. (
        1011378474 ; serial number
        10800 ; refresh
        3600 ; retry
        604800 ; expire
        86400 ; ttl
        )
mydomain.de.       IN      NS      www.mydomain.de.
www     in a 192.168.3.19
mydomain.de.       in mx 20 www.mydomain.de.
        in a 192.168.3.19

--
Hartwig Otten