On Fri, 25 Aug 2006 05:03:38 +0800
W B Hacker <[EMAIL PROTECTED]> wrote:

<<Snip>>

> The 'unique' manner of managing configuration is Debian-specific.
> 
> The problem is general:
> 
> - IF/AS/WHEN an MTA acts as a client to another MTA in MSA mode, *and* it 
> arrives on port 25, authentication is not ordinarily expected for traffic 
> destined TO the user-community on that server. It is seen as a 'distant' 
> correspondent - one of 'brazillions' who may have legitmate traffic for that 
> user community.
> 
> - However, IF/AS/WHEN said 'foreign' MTA attempts to submit traffic for OTHER 
> THAN users 'local' to the target host, it would ordinarily be treated as an 
> unauthorized relay attempt, and denied.
> 
> In order to be permitted to transit traffic to destinations NOT local to a 
> given 
> host, one or both of two tests must ordinarily be satisfied:
> 
> - The host attempting to submit must be recognized (by IP, matching pem 
> certs, 
> etc.) as an authorized relay source BY the intermediate host. Not bloody 
> likely 
> for an ISP host you do not control!
> 
> - The host attempting to submit must 'authenticate' with a UID:PWD valid on 
> the 
> intermediate host. This is exactly what your MUA ordinarily has to do when 
> submitting 'outbound' traffic, and may or may not be acceptable on port 25. 
> Port 587, with TLS, is a likely alternative.
> 
> Accordingly, the 'short answer' seems to be that for the intermediate 
> 'smarthost' in question, you will have to configure Exim to behave much as 
> your 
> MUA would do, i.e. use the expected port and protocol (TLS on 587?), and 
> supply 
> BOTH a UID and Password valid for that host.
> 
> IF said host allows you to send mail when traveling and attached via some 
> other 
> ISP's link, i.e with the correct UID:PWD, but a random source IP, then all 
> should be well. If NOT, then said host may *also* be allowing submission only 
> from valid UID:PWD who are also attached via its own 'backside' IP pool. Some 
> ISP do that, as it virtually guarantees that they can identify a rule 
> violator 
> by their own MAC address logs and session timestamps.
> 
> You can test this environment with your MUA to see if that is so.
> 
> Applying the appropriate settings to cause Exim to meet the ISP smarthost 
> submission needs for authentication UID:PWD, unfortunately, IS 
> Debian-specific 
> your case.
> 
> HTH,
> 
> Bill

Thanks for the detailed explanation. The smarthost in question is the Gmail 
SMTP server, which is available to anyone with a Gmail account, with no 
restrictions on the client's network segment location. As I mentioned, I have 
no problems with other MTAs (Sylpheed's built-in one, ssmtp) over the same 
link, so I suppose I must have made some Debian configuration mistake.
Anyway, I reinstalled and reconfigured (once again :) ) exim and this time I 
seem to have gotten it right. Thanks again for your help.

Celejar

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ssuds.sourceforge.net - Home of Ssuds and Ssudg, a Simple Sudoku Solver and 
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