Re: [exim] [new to exim] exim server not sending host name a…

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Szerző: Sam Walters
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Címzett: exim-users
Tárgy: Re: [exim] [new to exim] exim server not sending host name and failing verification.
Dave, Dominic, W B Hacker

>> I am assuming that;
>> * You're working on the mail server for aeroclub-beta.com.au.
>> * You are working on the machine with IP 203.132.28.33
>> * You want to send e-mail from info@???
>> * Such e-mail is being rejected by some recipient hosts
>> Is this correct?


Yes that's the issue. Thanks for your help.

Yes the server does not have PTR or MX entry yet. I am organising
that. So hopefully it will be sorted out in the next couple of days.

Thanks for your help.


Cheers

sam_w


On Tue, Mar 29, 2011 at 4:47 AM, W B Hacker <wbh@???> wrote:
> Dominic Benson wrote:
>>
>> On 28/03/11 17:31, Dave Evans wrote:
>>>
>>> On Mon, Mar 28, 2011 at 05:40:49PM +1100, Sam Walters wrote:
>>>>
>>>> Hi Dave
>>>>
>>>> Thanks for the background info on how to post on this email list.
>>>> I didn't notice the http://wiki.exim.org/DontObfuscate
>>>>
>>>> Yes you can probably get some info by looking at it directly: eg: exim
>>>> -bh 203.132.28.33 *the misconfigured server in question
>>>
>>> I've re-read your emails a few times but I'm afraid I'm still unclear
>>> as to
>>> what problem we're trying to resolve here.
>>
>> Likewise. I'm going to take a bit of a guess at the problem; tell me if
>> I'm wrong.
>>
>> I am assuming that;
>> * You're working on the mail server for aeroclub-beta.com.au.
>> * You are working on the machine with IP 203.132.28.33
>> * You want to send e-mail from info@???
>> * Such e-mail is being rejected by some recipient hosts
>> Is this correct?
>>
>>
>> It sounds like you're falling foul of sender verification. Basically, if
>> you don't accept delivery *to* an address, some users won't accept
>> delivery *from* it.
>>
>
> If that us indeed the correct sending IP, probably not a [ specific ] sender
> verification issue, (they are not common) ...but rather just the basic
> server 'credentials'
>
> There is no PTR RR showing up for IP 203.132.28.33
>
> $ host 203.132.28.33
> Host 33.28.132.203.in-addr.arpa. not found: 3(NXDOMAIN)
>
> Absent a PTR RR, it doesn't necessarily help traffic acceptability to have
> an MX RR.
>
> Whenever the connecting IP has no backpointer to the <domain>.<tld> the MX
> or A would be published *for*, any server checking rDNS would reject
> 'incoming' as a probable forgery.
>
> AFAIK rDNS checking is far more common than sender verification.
>
> Per below, an MX RR is a 'Very Good Idea' for any serious MTA as well.
>
> But a PTR RR OTOH, isn't just a good idea - it is pretty much *essential*.
>
> Needless to say, that presumes a fixed-IP, AND NOT one buried in the midst
> of an otherwise-dynamic IP block, ELSE rejection can occur even if a server
> is not doing rDNS checks, but IS checking dynamic-IP Remote Black Lists. Or
> both...
>
>
>> Aeroclub-beta.com.au has only an A record, resolving to 203.132.28.33.
>> That is an Exim 4.69 server, (so it seems consistent with what you
>> describe). That host won't accept delivery for info@???.
>>
>> If it should, then you need to configure it to. If it shouldn't, you
>> need an MX record to point to the host that should. (An MX record
>> wouldn't hurt in any case, A fallback isn't ideal).
>>
>> If it does, but info@ isn't one of those, then you should do one of:
>> a) Accept mail to info
>> b) Send from a different address
>> c) Use a different address as the return path (the -f option, if you're
>> calling from the local machine)
>> d) Accept, but blackhole mail to info@
>>
>> There are pros and cons to each of the above. Without more information
>> as to what you're trying to accomplish, I can't say which would be most
>> appropriate.
>>
>>
>
> I suggest getting both a PTR RR and an MX RR into your connectivity provider
> | IP blockholder DNS.
>
>
> HTH,
>
> Bill
>
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