Hi,
i'm pretty new to exim, but for the first part of your road to
understanding, i can try to help you.
Redirect routers seem to precise the way the messages are delivered but most
of them do not send a recipient to a transport (excepted maybe for filtering
routers), they just redirect (that's the key word) to other routers.
For example, in the aliasing router, the data field perform a kind of
rewriting so that the next time the recipient is analysed, the aliasing is
not called but the local_delivery is!
If someone has better explanations i would be very pleased to read them ;)
best regards
2010/3/21 exim.ml@??? <exim.ml@???>
> I've been trying to get my head round the redirect router for the last
> two days. I've gone over Phillip Hazel's book and the online
> documentation, but I just don't 'get' it.
>
> The part I am struggling with is the 'data' section. With the redirect
> router you don't specify a transport, I'm fine with that. What I don't
> understand is how the 'data' lookup actually decides the action to take
> on a message?
>
> I may be picking the wrong router for the job I want to do - but it's
> probably fundamental that I understand the logic and action taken.
>
> In my scenario I have multiple domains. In Postfix 'speak' I would have
> called them Virtual domains as they are 'hosted' but a single host may
> be dealing with multiple facets for them (handling mail/web traffic). In
> Phillip's Exim book the meaning of 'Virtual Domains' is different and is
> defined as 'a domain in which all the valid local parts are aliases for
> other addresses' - this is confusing the eggs out of me, so please
> forgive my terminology if it is incorrect.
>
> As far as the redirect 'data' section is concerned, in it's most simple
> example:
>
> data = ${lookup{$local_part}lsearch{/etc/aliases}}
>
> I would assume this would assign to 'data' the contents of the line
> returned from /etc/aliases. But how does it transport it to a mailbox or
> destination if it can't use a transport? I'm guessing that it is somehow
> implied - but it's going clear over my head.
>
> In my particular scenario I may have 40 or so 'hosted/virtual' domains.
> What I would like to achieve is the ability to redirect these dependent
> on data held in a MySQL database with the recipient email address as the
> search key.
>
> I guess I first populate a variable in the main section of the runtime
> conf with a list of domains the server accepts mail for:
>
> domainlist accepted_domains = mysql;select * from domains where
> domain='$domain'
>
> Then precondition the redirect router with:
>
> domains = domainlist
>
> The rough structure of the database in pseudo form would be:
> email_address final_destination destination_type
> ------------------------------------------------------------------------
> user@domain 1.2.3.4:25 direct to ip
> user2@domain /mailboxes/domain/user2 mailbox
> user@otherdomain host.otherdomain:2525 hostname lookup
> user2@otherdomain /mailboxes/otherdomain/user2 mailbox
>
> I'm assuming that 'redirect' is the right way to do this, that may be an
> incorrect assumption, but I'm struggling to see how I would redirect
> based on the 'final destination' and how that 'data' is parsed to
> transport it.
>
> Further complication comes from the old gateway cherry that is
> 'recipient verification'. Potentially final destinations can remove
> recipients and these changes may not reflect on my Exim gateway. This
> could leave it in the position of accepting a message it thinks it has a
> valid recipient for, and then having to bounce/backscatter it when it
> finds it can't deliver it. I know there are a number of ways to work
> with this, such as querying a final destination LDAP/AD - but this does
> not fit well with small customers running things like MailEnable on
> Windows. Postfix has a probing method with a short cache to deal with
> this scenario and looking at the Exim docs it appears that it has a
> similar recipient callout feature. Naturally I would like to roll this
> into my solution giving SMTP 5xx for 'no such user' before taking
> responsibility for the message as far as I possibly can.
>
> I apologise for the long winded question, but if I could clear up in my
> mind how the 'data' actually transports the mail, if it can query MySQL
> instead of a local alias file and if it's even the right router for what
> I need to do I would be most grateful for the input.
>
>
>
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