Actually describe the Debian-specific changes to dma.

diff --git a/README.Debian b/README.Debian
index d7c9bbbb16efee067dab74eb0a979f49fe1783e5..5ab251e2f4f9636d8b891f0968ff26dbab511768 100644 (file)
--- a/README.Debian
+++ b/README.Debian
@@ -1,6 +1,53 @@
 dma for Debian
 --------------
 
-<possible notes regarding this package - if none, delete this file>
+1. Deferred delivery by default
 
- -- Peter Pentchev <roam@ringlet.net>  Mon, 09 Feb 2009 13:28:53 +0200
+The dma mail transfer agent may operate in two modes - immediate and
+deferred.  In both cases, a new dma process is spawned for the delivery
+of each outgoing message, and this process lives on until the message is
+either successfully delivered or it times out after five days.
+
+In immediate delivery mode, the new dma process is spawned as soon as
+the message is submitted to the queue.  In deferred mode, which is
+the default for the Debian package, the message is left in the queue
+and will only be processed when dma is invoked separately with the "-q"
+command-line option.  I personally prefer this delivery mode - even though
+there may be slight delays, the queue must still be processed periodically
+anyway (if an immediate delivery is deferred, the message is still left
+on the queue), so there's no harm done in always doing it that way.
+
+Hence, the Debian package of dma installs a cron job that attempts to
+flush the queue every five minutes.  Note that this does NOT mean that
+message delivery will be attempted every five minutes!  Once the queue
+is flushed, a separate dma instance is spawned for each still-unhandled
+message, and it takes care of reasonable exponential back-off in case of
+delivery problems.
+
+2. Smarthost operation by default - needs to be configured!
+
+For the present, the dma mail transfer agent does not really handle
+direct MX lookups very well.  It is highly recommended that you only
+use it with a smarthost configured via the SMARTHOST directive in
+the /etc/dma/dma.conf file.  Note that the default SMARTHOST value of
+"mail.example.com" is virtually guaranteed not to work, as per
+the special status of the "example.com" domain according to RFC 2606 :)
+
+3. Double-bounce handling
+
+By default, the dma mail transfer agent does not really handle double
+bounces - it aborts the delivery with a critical syslog message.
+This, combined with the Debian package's default of "flush the queue
+every five minutes", may pose something of a strain on the mail server :)
+Thus, the Debian version of dma adds a new feature - you may specify
+an external program to handle double bounces with the DBOUNCEPROG 
+directive in the /etc/dma/dma.conf file.  Also included is a sample
+program, dbounce-simple-safecat, which uses the safecat utility to
+copy the bounce message into a Maildir-structured storage,
+/var/spool/mail/dma-bounces by default.  Its functionality will be
+extended in the future to allow more configuration and to possibly
+parse the message to make it actually mailbox-compatible - for the present,
+the copied file still has the dma internal format, which is plain text,
+but is not really a mailbox :)
+
+ -- Peter Pentchev <roam@ringlet.net>  Tue, 10 Mar 2009 12:04:48 +0200