Re: [exim] alias, mailer transport, rewriting....

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Autor: Philip Hazel
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A: Michael Nguyen
CC: exim-users
Assumpte: Re: [exim] alias, mailer transport, rewriting....
On Mon, 6 Dec 2004, Michael Nguyen wrote:

> RCPT TO:<michael2812>


That is syntactically invalid. RFC 2821 (which defines SMTP) specifies
that addresses in the commands must have both a local part and a domain.

> I've found that other MTAs will not send an email without a domain name
> attached to the end.


They are following the RFC.

> Will Exim let me do this? Will Exim let me setup a system as I've
> described above?


No. It also follows the RFC. Exim does have an option for *accepting*
addresses without domains, so that it can support broken clients, but
you cannot configure to behave in this broken way as a sender.

> What some MTAs do is the following:
>
> - Email comes in for michaeln@???
> - An alias lookup is performed and finds that michaeln@??? points
> to michael2812


In the case of Exim, the result of the alias lookup will be
michael2812@???. The domain can be explicitly specified, can be
defaulted, or can be the incoming domain (twentyten.org). It could even
depend on the local part. Your choice, but there has to be a domain.

> - A transport lookup is also performed and finds that michael2812 goes to
> server8.test.spam


Again, it isn't just michael2812 that is looked up, it is
michael2812@??? (and it can yield different results for
michael2812@??? compared with michael2812@???).

> - The MTA then sends to the email to the specified server as
> michael2812@???


To do that you would have to arrange that what I called "some.domain"
above is really "server8.test.spam".

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book