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Postfix Archives: Virtual local delivery agent

Virtual local delivery agent

Subject: Virtual local delivery agent
From: Andrew McNamara (andrewmconnect.com.au)
Date: Sat Jan 22 2000 - 21:32:27 CST

I've finally gotten around to cleaning up my hacked local delivery
agent - this code is designed for ISP's who offer virtual mail
hosting. It looks up the location, uid and gid of user mailboxes via
separate maps, and the mailbox location map can specify either mailbox
or maildir delivery (controlled by trailing slash on mailbox name).

The agent does not support aliases or .forwards (use the virtual table
instead), and therefore doesn't support file or program aliases. This
choice was made to simplify and streamline the code (it allowed me to
dispense with 70% of local's code - mostly the bits that are a security
headache) - if you need this functionality, this agent isn't for you.

It also doesn't support writing to a common spool as root and then
chowning the mailbox to the user - I felt this functionality didn't fit
with my overall aims.

Before I release the code, I need some hints about fine tuning:

- I've called the agent "virtual", but I'm slightly concerned people
  will confuse this with the virtual table. Other suggestions are
  welcome.

- Currently the agent will deliver to any file with any uid (other than
  root) returned by the maps, which leaves me with an uneasy feeling.
  Possible options include specifying a minimum uid in the config file
  (i.e., set this to one greater than your highest system account), and
  specifying a mailbox prefix in the config file (i.e., can only write
  to files under this path). I'll probably implement both of these, but if
  anyone has any other suggestions, please make them. I'm also concerned
  that there is no safe default for these variables (although a default
  that knobbles the agent unless the user sets something sane would be a
  reasonable choice).

- Currently every recipient is looked up in the uid map and the gid map. If
  a site is running with fixed uid and/or fix gid across all their dialup
  users, then they could specify a fixed map that returned these values. Do
  people consider it worthwhile having a config file option to specify
  fixed uid/gid instead?

- To perform a delivery, the agent has to look up the mailbox path map, the
  uid map, and the gid map. Does this tie in with how people would like to
  use the agent with LDAP, or is there a better way of doing this (maybe
  one map lookup that returns 3 delimited fields)?

- dot locking is controlled with a config option, but I'd be surprised if
  anyone used dot locking in this context. At this point, I'm inclined to
  leave the functionality there, but default the option to "no".

Anything else people want? Questions?

 ---
Andrew McNamara (System Architect)

connect.com.au Pty Ltd
Lvl 3, 213 Miller St, North Sydney, NSW 2060, Australia
Phone: +61 2 9409 2117, Fax: +61 2 9409 2111

This archive was generated by hypermail 2b27 : Sat Jan 22 2000 - 21:34:49 CST