[ale] Bellsouth Sendmail Fix

[James CE Johnson]

> Any way a Postfix user can do this?

You can use exactly the same technique.

In your /etc/postfix/main.cf change this:
    relayhost = mail.bellsouth.net

to this:
    relayhost = [mail.bellsouth.net]

>
> Stephen Touset
>
> Joe Steele wrote:
>
>>On Wednesday, July 02, 2003 1:35 AM, Ryan Neily wrote:
>>
>>
>>>I tried this below, and it seems to work for me as well.  Anyone know
>>> why?
>>>
>>>
>>>
>>
>>Every time sendmail parses a recipient address, the end result is a
>> {MAILER, HOST, USER} 3-tuple.  The processing of the message is then
>> passed to the selected MAILER, along with the HOST and USER info.  If
>> the resulting MAILER is an '[IPC]' mailer (e.g., when the mailer is
>> 'smtp' or 'relay'), then the HOST name has MX expansion performed via
>> DNS.  However, this MX expansion can be bypassed by putting square
>> brackets around the host name.
>>
>>All of the above is irrespective of whether a SMART_HOST is used,
>> because the sendmail program doesn't actually know anything about
>> SMART_HOSTs.  SMART_HOSTs are a feature of the m4 processing which
>> adds rulesets that end up putting the SMART_HOST name into the HOST
>> name which is passed to the MAILER.  Consequently, SMART_HOSTs are
>> subject to MX expansion just like any other host name.
>>
>>The Bellsouth server which you are using as a SMART_HOST
>>(mail.bellsouth.net) has the following MX records:
>>
>>mail.bellsouth.net      preference = 0, mail exchanger =
>> mx01.mail.bellsouth.net mail.bellsouth.net      preference = 0, mail
>> exchanger = mx00.mail.bellsouth.net
>>
>>So as a consequence of MX expansion, sendmail is attempting to relay
>> your mail to mx0[01].mail.bellsouth.net, rather than to
>>mail.bellsouth.net.  The problem is that mail.bellsouth.net is
>>configured to relay mail received from Bellsouth IP addresses,
>>whereas mx0[01].mail.bellsouth.net are configured to accept mail
>> addressed to Bellsouth customers but not to relay mail.
>>
>>As Jeff Brodnax has shown, using [mail.bellsouth.net] as the
>>SMART_HOST solves the problem by avoiding MX expansion so that
>>sendmail relays the mail directly to mail.bellsouth.net.
>>
>>Ryan Neily solved it in a more circuitous fashion by using port
>>forwarding and by using localhost as the SMART_HOST.  Sendmail thinks
>> it's relaying the mail to localhost, but in reality the connection is
>> forwarded to mail.bellsouth.net.
>>
>>--Joe
>>
>>
>>
>>
>>
>>>On Wed, 2 Jul 2003, Ryan Neily wrote:
>>>
>>>
>>>
>>>>So you're SMART_HOST line in your sendmail.mc file reads:
>>>>
>>>>define(`SMART_HOST', [mail.bellsouth.net])
>>>>
>>>>???
>>>>
>>>>On Wed, 2 Jul 2003, Jeff Brodnax wrote:
>>>>
>>>>
>>>>
>>>>>On Tue, Jul 01, 2003 at 11:26:49PM -0400, Ryan Neily wrote:
>>>>>
>>>>>
>>>>>>If this gets posted, I've fixed the Bellsouth no-relay problem that
>>>>>> people has been complaining about.  I used some of the tips of
>>>>>> James CE Johnson which is using Postfix.  My solution is using
>>>>>> Sendmail, but works much the same...
>>>>>>
>>>>>>I added a redirect rule to my IPtables firewall script that
>>>>>> redirects any traffic coming from port 26 on the localhost
>>>>>> interface to the bellsouth SMTP server on port 25.  I used this
>>>>>> iptables command:
>>>>>>
>>>>>>$IPTABLES -t nat -A OUTPUT -p tcp -d 127.0.0.1 --dport 26 -j DNAT
>>>>>> --to-destination 205.152.59.16:25
>>>>>>
>>>>>>and then added the following directives to my sendmail.mc, m4'd it
>>>>>> to sendmail.cf and it seems to be working:
>>>>>>
>>>>>>
>>>>>Hi I am a lurker, just wanted to share the work around I found for
>>>>> the no relaying by bellsouth.net.  I added brackets.. ie.
>>>>>[mail.bellsouth.net] to my sendmail.mc as the smart host.  I have no
>>>>> idea what this does, other than it doesn't use the mx anymore just
>>>>> right through the main smtp server.   Relaying works again.
>>>>>
>>>>>

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