Re: Qmail-- Exim

[Brian Longwe <blongwe at psg.com>]

On Sun, 17 Jun 2001, Brian Candler wrote:

> On Sun, Jun 17, 2001 at 01:08:49PM +0300, Sematimba Noah K wrote:
> One of the strange things about virtusertable in sendmail, I think, is that
> the user ends up with multiple addresses in other people's domains. To take
> this example:
> 
> user1 at customer.com        customerisp1
> 
> If I understand rightly, 'customer.com' has to go in sendmail.cw. As a
> result, the customer can also receive mail as <customerisp1 at customer.com>,
> <customerisp1 at mailserver.isp.net> and in fact
> <customerisp1 at any-domain-in-sendmail.cw>
> 
the order in which mail is handled is as follows:

1) first, incoming mail is checked against domains listed in the
'mailertable'; matches are passed on, failures are rejected
2) next addresses matching entries in the virtusertable are
delivered, addresses that miss are passed on, if the address had
nbi.ispkenya.com as the domin but the user is not listed in the
virtusertable, then the mail is rejected with a 'user unknown'
3) remaining addresses are matched against the sendmail.db, if there
is a match, the message is delivered, if not, the mail is rejected
with a 'user unknown'

In terms of organisation, the virtusertable has *only* entries with domain
as nbi.ispkenya.com.

the sendmail.db has entries for all other domains

for an entry in the sendmail.db to work it *must* have an entry in the
virtusertable (with the local domain nbi.ispkenya.com)

the sendmail.db has added functionality in that it allows me to do
POP-based mail gateways i.e. where all mail for a certain domain is routed
to a single mailbox, which is then popped by the customers mailserver
(Exchange, Mdaemon,Fetchmail  etc...)

I use an automated ISP Billing and Administration system which is
web-based. User accounts are created by low-tech admin staff (mainly the
cashier and two operations girls). The system the uploads scripts that
create the account in /etc/passwd, make entries in the virtusertable and
create the hash database of virtusertable. 

'virtual Domains' are all done in the sendmail.db; this part  is not done
by the automated system. One of my sysadmins is notified by the operations
staff that a certain cusomter has subscribed for multiple 'domain-based'
emails, the list of local accounts (nbi.ispkenya.com) associated iwth the
customer is attached- the dmain name is also given. The sysadmin then
editss the sendmail.db and  and puts in the entries e.g.:

user1 at customerdomain.com			user1 
user2 at customerdomain.com			user2

the right hand side delivery will not work *unless* a corresponding entry
has been made in the virtusertable (because this is how accounts are
automatically put into the /etc/passwd)

So, from the above, if you read carefully, you wil probably see that my
main constraint is my automated system. Not a constraint really, because I
can write perl or shell scripts to do whatever needs to be done on the
server side.

As you can see, I also customised my sendmail so that users don't have
email addresses on each others domains. Due to the order in which the
rulesets are applied, if a user does not have an explicit entiry for a
specific domain *and* a corresponding local account, the message is
rejected..

Sorry for being so wordy, but I hope the functionality isclear now.


Longwe


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