Mailing List Archive: What does exim do with malformed messages?

What does exim do with malformed messages?

Nov 29, 2023, 7:42 AM

Post #1 of 3 (92 views)

If a malformed mail message shows up by SMTP (not local sendmail or submission),
will exim generally try to clean it up or just pass it along?

I see the discussion of submission mode in chapter 48 of the manual and all the
options about when to run it and what to tell it to do, but in practice, will a
typical system clean everything up, just locally submitted stuff, or soemthing
else? Tnx.

I'm thinking of stuff like this that might come from a badly written gateway:

From: fred at example.com
Message-Id: something@somethingelse
Date: Tuesday, 28 Nov 2023 18:17:05 GMT

R's,
John

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Re: What does exim do with malformed messages? [ In reply to ]

exim-users at lists

Nov 30, 2023, 1:44 AM

Post #2 of 3 (92 views)

Permalink

On Wed, 29 Nov 2023, John R Levine via Exim-users wrote:

> If a malformed mail message shows up by SMTP (not local sendmail or
> submission),
> will exim generally try to clean it up or just pass it along?
>
> I see the discussion of submission mode in chapter 48 of the manual and all
> the
> options about when to run it and what to tell it to do, but in practice, will
> a
> typical system clean everything up, just locally submitted stuff, or
> soemthing
> else? Tnx.
>
> I'm thinking of stuff like this that might come from a badly written gateway:
>
> From: fred at example.com
> Message-Id: something@somethingelse
> Date: Tuesday, 28 Nov 2023 18:17:05 GMT
>
> R's,
> John

If I remember correctly, the basic philosophy is to
pass it along, but there are places where particular
headers do get sanitised or missing headers added.

--
Andrew C. Aitchison Kendal, UK
andrew@aitchison.me.uk

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Re: What does exim do with malformed messages? [ In reply to ]

exim-users at lists

Nov 30, 2023, 2:35 AM

Post #3 of 3 (92 views)

Permalink

On 11/29/23 15:42, John R Levine via Exim-users wrote:
> If a malformed mail message shows up by SMTP (not local sendmail or submission),
> will exim generally try to clean it up or just pass it along?
>
> I see the discussion of submission mode in chapter 48 of the manual and all the
> options about when to run it and what to tell it to do, but in practice, will a
> typical system clean everything up, just locally submitted stuff, or soemthing
> else? Tnx.

Exim's submission mode is set on a per-message basis
under the control of the local configuration.

The example config file in Exim git sets submission
for
a) anything received from a named-list of hosts
(the "list" can be static, can be a DB lookup).
The list is called "relay_from hosts" which is
a hint as to the intended use - but names are only
interpreted by the config, not meaningful to the
Exim code.
b) anything received under SMTP authentication

--
Cheers,
Jeremy

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