Linux Mail-Queue mini-HOWTO
 Leif Erlingsson, [email protected], Jan P Tietze, jpti
 [email protected]
 v2.02, 3 September 1997, 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.


 ______________________________________________________________________

 1.  Introduction

 The document is written by two authors. The NON dial-on-demand
 solutions part (oldest part) is written by Leif Erlingsson
 <[email protected]>, and the newer dial-on-demand solutions part is
 written by Jan P Tietze <[email protected]>.



 2.  NON dial-on-demand solutions PART

 Written by Leif Erlingsson <[email protected]>.

 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 <[email protected]>'', 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 <[email protected]>
      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 <[email protected]>'', Subject:
 ``Menu support suggestions''



 3.  Dial-on-demand solutions PART

 Written by Jan P Tietze <[email protected]>.

 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.

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