Author: W B Hacker Date: To: exim users Subject: Re: [exim] ACL, transport, & SpamAssassin
Ian Eiloart wrote: > On 7 Feb 2012, at 16:48, Antonio Leding wrote:
>> Hi Heiko,
>>
>> Thanks very much for this information - so two more questions for
>> you and the community:
>>
>> 1) It seems that ACL is faster when compared to TRANSP?ORT - is
>> this true?
>
> ACLs are Access Control Lists that chiefly determine whether you want
> to accept, defer or reject the email. That's why you want to do your
> SpamAssassin filtering here. It's also a good place to do malware
> filtering, with ClamAV for example.
>
> ACLs do have other purposes, though, such as passing information to
> routers, transports, or your log file.
>
> Routers determine how you're going to handle the message. But you
> don't get to the router until the ACLs have decided that the message
> is OK. The main purpose of your routers is to select a TRANSPORT to
> do the actual delivery.
>
> Transports do the actual delivery of your message, so they're the
> last objects to handle the message. Transports might pass the message
> to another mail server using SMTP or LMTP, or deliver it to a local
> file that's accessible to an IMAP server, or something else. There
> are lots of possibilities, and it's the ROUTERS that decide which
> TRANSPORT to use.
>
>> 2) Is Exim planning on removing the ability to perform the
>> TRANSPORT type of operation?
>>
>
> AFAIK, you don't have to have a transport in your Exim configuration,
> but it would be unusual.
>
>
>
Technically true.
But with no routers or transports, eg: run 'queue_only' Exim DOES become
a 'collector and hoarder'.
It ordinarily wants another critter, or a separate Exim instance, to do
delivery FROM the queue.
Even leaving the queue as a dumping ground for on-box logfiles makes for
cumbersome parsing and fs bloat.
