On 27.01.18 11:16, CP wrote:
I'm trying to eliminate a problem with duplicate emails in alias
expansion and I have seen that some (local generated and SMTP also)
messages don't have the Message-ID header .
I should add that such duplicity should not happen when using aliases.
Also, it may happen that two people get different copies of the same mail
(e.g. from this list).
Are you sure your duplicities can't be fixed other way?
I'm reading in in postconf
that there is a configuration option always_add_missing_headers that
does exactly that. If I enable this option do I get in any risk of
braking anything in my existing setup ? The manual refers that " this
may break DKIM signatures that cover non-existent headers" but I'm not
sure if that refers to local generated messages or everything received my
SMTP. I'm not currently using DKIM in my setup.
On 01/27/2018 12:09 PM, Matus UHLAR - fantomas wrote:
If you receive dkim-signed mail without message-id, but the dkim signature
will claim it contains message-id too (does this happen?), and when you
add it, the message will not pass the check (including your message-id
changes the hash).
On 27.01.18 13:21, CP wrote:
So far I have only seen messages without the message-id header , is there
some way to check for what you're describing above in received message
headers ?
this is from your mail:
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=gmail.com; s=20161025;
h=subject:to:references:from:message-id:date:user-agent:mime-version
:in-reply-to:content-transfer-encoding:content-language;
you see message-id there.
if such DKIM header includes Message-Id: but message has none, DKIM breakage
may happen when you add it.
this should not be a problem if you aren't resending the mail to outside,
and can be avoided by checking the DKIM before message-id is added
and never
later.
Usually I don't resend the message but users might forward the message to
an outside recipient, this is not the case I hope ?
no.
Checking DKIM is done by postfix ? any further info or reading
about this ?
as you configure, usually spam filter checks for it.
if you are going to add message-id as postfix level you apparently need
implement before that, DKIM milter probably.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
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