Internal sendmail problems

Mark Blackman mark at blackmans.org
Wed Jan 2 16:45:13 GMT 2008


On 2 Jan 2008, at 16:40, Mark Blackman wrote:

>
> On 2 Jan 2008, at 16:26, Mark Blackman wrote:
>
>>
>> On 2 Jan 2008, at 16:15, O'Connor, Kevin wrote:
>>
>>> Mark,
>>>
>>> I ran tcpdump as you suggested and I'm seeing lots of the following
>>>
>>> 15:53:08.372068 IP (tos 0x0, ttl  64, id 25688, offset 0, flags  
>>> [none],
>>> proto: UDP (17), length: 57, bad cksum 0 (->ac3a)!)  
>>> 10.10.0.4.58007 >
>>> 10.10.86.10.53: [bad udp cksum 5042!]  46723+ AAAA?exchcluster. (29)
>>> 15:53:08.372708 IP (tos 0x0, ttl 126, id 7951, offset 0, flags  
>>> [none],
>>> proto: UDP (17), length: 57) 10.10.86.10.53 > 10.10.0.4.58007:  
>>> [udp sum
>>> ok]  46723 ServFail q: AAAA? exchcluster. 0/0/0 (29)
>>>
>>> I have assumed that sendmail on FreeBSD has sendmail's
>>> WorkAroundBrokenAAAA option but this appears to either not be the  
>>> case
>>> or the option fails to resolve the IP6 issue with W2K3 DNS servers.
>>>
>>> At this point any and all suggestions (That do not involve  
>>> removing MS
>>> DNS and/or Exchange) would be welcome.
>>
>> http://zaib.as/node/8
>>
>> appears to spell out the issue. I'd suggest rebuilding sendmail
>> as per..
>>
>> http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2006-07/ 
>> msg01020.html
>>
>> *OR*
>>
>> use the ports system to replace sendmail with a different MTA,
>> my personal preference is postfix.
>>
>> Possibly, you could rebuild the resolver library with different  
>> options
>> as well. To be honest, I'm surprised this issue still exists over  
>> a year
>> later.
>>
>> - Mark
>
> There's a line in /etc/mail/sendmail.cf, whose removal may work to  
> fix this case.
>
> Try deleting the line with
>
> O DaemonPortOptions=Name=IPv6, Family=inet6, Modifiers=O
>

In fact, re-reading the config. more carefully, that's the listening  
daemon and
that's not the problem. Try *uncommenting* the following line.

#O ClientPortOptions=Family=inet, Address=0.0.0.0

That might force sendmail to use just inet instead of attempting  
inet6 when sending and
avoid the AAAA lookup.

I hate sendmail anyway, so I've not tested anything. :)

- Mark





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