  Linux Mail-Queue mini-HOWTO
  Leif Erlingsson, leif@lege.com, Jan P Tietze, jpti­
  etze@mail.hh.provi.de
  v2.03, 2001-12-17, sendmail 8.8.7

  Queue Remote Mail + Deliver Local Mail The Configuration Changes Nec­
  cessary to Make Sendmail Deliver Local Mail ***Now*** While Stashing
  Remote Mail in The Queue Until "I Say So".
  ______________________________________________________________________

  Table of Contents


  1. Introduction

  2. NON dial-on-demand solutions PART

     2.1 Starting sendmail
     2.2 Configuring sendmail
        2.2.1 Configuring sendmail.cf directly, for trivial configurations
        2.2.2 Configuring sendmail.cf using m4 source
     2.3 Menu support suggestions

  3. Dial-on-demand solutions PART

     3.1 Configuring sendmail.cf
        3.1.1 Configuring sendmail.cf directly, for trivial configurations
        3.1.2 Configuring sendmail.cf using the m4 source.
     3.2 Adding dial delay
        3.2.1 Configuring sendmail.cf directly
        3.2.2 Configuring sendmail.cf using m4 source

  4. Delivering e-mail

     4.1 How to have e-mail delivered at special times.

  5. License



  ______________________________________________________________________

  1.  Introduction

  The document is written by two authors. The NON dial-on-demand
  solutions part (oldest part) is written by Leif Erlingsson
  <leif@lege.com>, and the newer dial-on-demand solutions part is
  written by Jan P Tietze <jptietze@mail.hh.provi.de>.



  2.  NON dial-on-demand solutions PART

  Written by Leif Erlingsson <leif@lege.com>.

  The original version of this part contained a lot of unnecessary
  stuff.  This is all it takes, really...


  2.1.  Starting sendmail

  Slackware et al:        /etc/rc.d/rc.M:



  echo "Starting sendmail daemon (/usr/sbin/sendmail -bd -os) [queue only mode]..."
  /usr/sbin/sendmail -bd -os      # NOT "-bd -q 15m", the "standard" flags!



  RedHat et al:           /etc/rc.d/init.d/sendmail.init:



       echo -n "Starting sendmail: [queue only mode]"
       daemon sendmail -bd -os         # NOT daemon sendmail -bd -q1h



  The -os is not really essential, all it does is this:



       SuperSafe [s] Be super-safe when running things, i.e.,
               always instantiate the queue file,  even  if
               you are going to attempt immediate delivery.
               Sendmail always instantiates the queue  file
               before  returning  control  the client under
               any  circumstances.   This   should   really
               always be set.



  This should already be configured in the default sendmail.cf anyway.


  2.2.  Configuring sendmail

  Serious sendmail users use the m4 source for this. I recommend this
  solution if you ever plan on upgrading sendmail and also make anything
  but trivial changes to sendmail.cf.

  If you never intend to fix sendmail so envelope return headers et al
  works even though you might be on dynamic dial in IP or something,
  then you may not need to get the m4 source.


  2.2.1.  Configuring sendmail.cf directly, for trivial configurations

  This way of doing things is extremeley version dependent vs.
  sendmail.cf versions. The following solution is *only* valid for
  sendmail-8.8.x.

  Edit /etc/sendmail.cf:



       # avoid connecting to "expensive" mailers on initial submission?
       O HoldExpensive=True



  ... later ...

       #####  @(#)smtp.m4      8.33 (Berkeley) 7/9/96  #####

       Msmtp,          P=[IPC], F=mDFMuXe, S=11/31, R=21, E=\r\n, L=990,
                       T=DNS/RFC822/SMTP,
                       A=IPC $h
       Mesmtp,         P=[IPC], F=mDFMuXae, S=11/31, R=21, E=\r\n, L=990,
                       T=DNS/RFC822/SMTP,
                       A=IPC $h
       Msmtp8,         P=[IPC], F=mDFMuX8e, S=11/31, R=21, E=\r\n, L=990,
                       T=DNS/RFC822/SMTP,
                       A=IPC $h
       Mrelay,         P=[IPC], F=mDFMuXa8e, S=11/31, R=61, E=\r\n, L=2040,
                       T=DNS/RFC822/SMTP,
                       A=IPC $h



  The important flag above is ``e''. Don't fuss if the other flags look
  different in your file. Keep your flags as-is, only add ``e'' to your
  flags according to the above examples, unless it's there already.
  ``e'' marks the mailers as ``expensive''.


  2.2.2.  Configuring sendmail.cf using m4 source

  In the following I will, for simplicity, assume that the sendmail
  version is 8.8.7. If you have a different version, replace 8.8.7 with
  that version number below! Also, the instructions will not work for
  older versions of sendmail. Get the latest sendmail!


  Download the sendmail source.  Try ``http://WWW.Sendmail.ORG'' or
  possibly ``ftp.sendmail.org''.


  I also recommend that you obtain my patch for allowing envelope sender
  reverse aliasing and other nice stuff to really make you take control
  over your mail environment.

  Write to ``Sendmail Patch <sendmail@lege.com>'', Subject:
  ``sendmail-8.8.7'', if 8.8.7 is your sendmail version.

  They are also available from ``http://www.lege.com'', as is the sgml
  source of this mini-HOWTO!

  You don't have to get my patches in order to get ``Queue Remote Mail +
  Deliver Local Mail'' to work. My patches solve other things. But I
  just thought this would be a nice place to mention them, as many Linux
  users will find them extremely useful.  (They will even give you
  properly working virtual domains, if you like. The virtual domains
  don't have to be ``local''. They will give you ``xaliases'', or in
  other words ``reverse aliasing''.)

  Unpack the sendmail source. You may get /usr/src/sendmail-8.8.7/.  cd
  /usr/src/sendmail-8.8.7/cf

  Now overlay my patch, if you want it, otherwise skip this step: If you
  don't want to use procmail as Local Delivery Agent, save away your
  /usr/src/sendmail-8.8.7/cf/ostype/linux.m4 before doing this...  Save
  my patch to ``/tmp/sendmail-8.8.7-cf-cpio-idcmu.gz'', then...



  cd /usr/src/sendmail-8.8.7/cf
  gzip -dc < /tmp/sendmail-8.8.7-cf-cpio-idcmu.gz | cpio -idcmu



  If you didn't want to use procmail, write back the saved copy of
  /usr/src/sendmail-8.8.7/cf/ostype/linux.m4 again.

  And regardless of if you applied my patch or not, you must make sure
  these lines or very similar ones are added to
  /usr/src/sendmail-8.8.7/cf/cf/yourhostname.smtp.mc (but if you applied
  my patch you may want to investigate filenames containing the word
  ``elijah'', under /usr/src/sendmail-8.8.7/cf):



       dnl # Defer Delivery to "expensive" mailers until next time the
       dnl # queue is processed using "O HoldExpensive=True" and make
       dnl # sure smtp mailers are "expensive".
       dnl # (See original "sendmail" book Chapter 30: Options,
       dnl # "Oc - Don't connect to expensive mailers", or
       dnl # 2nd Edition "sendmail" book Chapter 34.8.29,
       dnl # "HoldExpensive (c), Queue for expensive mailers".)
       dnl #                           / Leif Erlingsson <leif@lege.com>
       define(`confCON_EXPENSIVE', `True')
       define(SMTP_MAILER_FLAGS, e)
       MAILER(local)dnl
       MAILER(smtp)dnl



  2.3.  Menu support suggestions

  The 1.x versions of this document contained Menu support suggestions
  for /var/X11R6/lib/fvwm/system.fvwmrc. I have dropped those in the
  current version, but they are available on request:


  Write to ``Menu support suggestions <fvwmrc@lege.com>'', Subject:
  ``Menu support suggestions''



  3.  Dial-on-demand solutions PART

  Written by Jan P Tietze <jptietze@mail.hh.provi.de>.

  Many Linux users access the Internet through a dialup line, and many
  have decided to implement dial-on-demand facilities on their system.
  That is, whenever an IP packet of some sort has to leave the local
  network or the local host, the link to an Internet Service Provider
  (ISP) will automatically be established. The link will be dropped
  after some period of time that no packet has travelled across.

  Although this is very comfortable and cost effective, there is one
  special case in which this is neither comfortable (as the time to
  bring up a "traditional" modem dialup is very noticeable) nor cost
  effective, and this is sending e-mail. E-Mail is commonly sent by
  SMTP, either delivered by your own system or through a SMTP host on
  the Internet that usually resides in your ISP's network.

  With dialup lines, every time you send a message the link will have to
  be brought up. This is quite okay if you send only one message, but if
  you happen to create and send multiple messages, bringing up the line
  more than once can be tedious and cost ineffective. Also, if your ISP
  imposes limits as to what times you are allowed to login, this would
  also restrict you to postpone messages at certain times of the day,
  and you would have to manually send them later.

  Section 1 of this document will solve the situation, however in
  situations where an external DNS lookup would cause the link up, the
  link will still be established even if e-mail is just being queued.
  The reason is that sendmail wishes to "canonify" host names.

  The solution to this problem is twofold: First, we'll have to
  moderately change sendmail.cf. And then we have to define the process
  of actual mail delivery. Personally, I prefer to have cron do the job
  for me and describe the necessary changes below.


  3.1.  Configuring sendmail.cf

  For the reasons stated in [1.2], I recommend modifying the m4 sources
  instead of editing sendmail.cf directly. It will actually save you a
  lot of hassle and make configuration changes more verbose.

  First, perform all the changes described in the first part of this
  document. Then go through the dial-on-demand specific stuff.


  3.1.1.  Configuring sendmail.cf directly, for trivial configurations

  Configuring directly is highly impractical and anything but verbose,
  but obviously, this is your decision.

  Close to very bottom of your sendmail.cf should be a line that reads:



       R$* < @ $* $~P > $*             $: $1 < @ $[ $2 $3 $] > $4



  Precede that line with a "#" so that it reads



       #R$* < @ $* $~P > $*            $: $1 < @ $[ $2 $3 $] > $4



  3.1.2.  Configuring sendmail.cf using the m4 source.

  Add the following line to
  /usr/src/sendmail-8.8.7/cf/cf/yourhostname.smtp.mc:



       FEATURE(nocanonify)dnl



  Your final sendmail.cf can then be built by issuing the following
  commands. Remember to always back up your old /etc/sendmail.cf before
  installing the new one:
       cp /etc/sendmail.cf /etc/sendmail.cf.bak
       cd /usr/src/sendmail-8.8.7/cf/cf
       m4 yourhostname.smtp.mc > /etc/sendmail.cf



  3.2.  Adding dial delay

  It is oftentimes useful, especially when using modem lines, to have a
  dial delay installed. This means that if sendmail tries to initiate a
  connection in an attempt to send an e-mail (and this causes the line
  to go up) but the link actually takes more time to get established
  than what sendmail thinks should be a reasonable timeout, sendmail
  will simply wait some seconds and then retry.


  3.2.1.  Configuring sendmail.cf directly

  Somewhere in your sendmail.cf could be a line that would read:



       #O DialDelay=10s



  (or very similar). Delete the ``#''. If there's no ``#'' at the
  beginning of the line, things should be considered okay (it just means
  this had already been enabled before).

  If there is no such line in your sendmail.cf, add one (it is a wise
  thing to do to add this in the "options" part of the file):



       O DialDelay=10s



  Now change the ``10s'' part to the number of seconds you deem
  suitable.


  3.2.2.  Configuring sendmail.cf using m4 source

  Add the following line to
  /usr/src/sendmail-8.8.7/cf/cf/yourhostname.smtp.mc:



       define(`confDIAL_DELAY',`10s')



  Now change the ``10s'' part to the number of seconds you deem
  suitable.

  Your final sendmail.cf can then be built by issuing the following
  commands. Remember to always back up your old /etc/sendmail.cf before
  installing the new one:

       cp /etc/sendmail.cf /etc/sendmail.cf.bak
       cd /usr/src/sendmail-8.8.7/cf/cf
       m4 yourhostname.smtp.mc > /etc/sendmail.cf



  4.  Delivering e-mail

  E-Mail delivery can be invoked by issuing the command "sendmail -q".
  For those who are interested in what sendmail actually does, "sendmail
  -q -v" will give a more verbose version of the delivery process.

  It is very convenient to automate the process of e-mail delivery. A
  tool commonly used for this process is cron.


  4.1.  How to have e-mail delivered at special times.

  Edit your crontab:



       crontab -e



  Add lines of the form:



       05 18-23,0-7    * * Mon,Tue,Wed,Thu,Fri /usr/sbin/sendmail -q
       05 *            * * Sat,Sun             /usr/sbin/sendmail -q



  Please refer to the crontab man page (available through "man 5 \
  crontab") for further information. I think the format is pretty
  obvious. The example crontab entries shown above send e-mail (if, and
  only if, e-mail is available from the queue) 5 minutes after an hour
  on weekdays, starting at 6:05 pm, and stopping at 7:05 am.  On
  weekends, e-mail is delivered 5 minutes after an hour, starting at
  12:05 pm on Saturday, and stopping 11:05 pm on Sunday.

  As a dial-on-demand user, it is sometimes desirable to have your
  system collect your e-mail via the POP3 protocol at certain times of
  the day. You could therefore add an entry similar to the following to
  your crontab:



       0 21            * * * popclient -3 -u <your pop3 user name
       goes here> -p <put your password here> -o /var/spool/mail/<the user
       on your system that should receive the collected e-mail>
       <mailhost.somedomain.com>



  Of course, this should all go on a single line.

  Then, save the file and leave the editor. The crontab should now be
  installed.
  5.  License

  This document is distributed under the terms of the GNU Free
  Documentation License.  You should have received a copy along with it.
  If not, it is available from http://www.fsf.org/licenses/fdl.html.



