Re: [exim] ACL, transport, & SpamAssassin

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.



--
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148