[comp.mail.sendmail] Sendmail and NFS

rdr@cl4.alliant.com (Roger Roles) (12/14/90)

In the configuration file (/usr/lib/sendmail.cf) you should find lines which
look similar to the following:

# Remote mode - send through server if mailbox directory is mounted
OR

If you comment this out, you should get the behavior you expect. Please note
that this is not necessarily a recommended setup and I am not guaranteeing
how it will work. I would be uncomfortable to have more than one machine
writing into a mail spool directory.
--
Roger D. Roles		rdr@Alliant.COM, alliant!rdr
Alliant Computer Systems Corporation	508-486-1211

mzellers@starnet.uucp (Mark Zellers) (12/16/90)

In article <4386@alliant.Alliant.COM> rdr@cl4.alliant.com (Roger Roles) writes:
>
>I would be uncomfortable to have more than one machine
>writing into a mail spool directory.

I'll try your suggestion re: the OR flag.  If I don't have multiple
machines writing into a single spool directory, is there another way I
can acheive the same effect?  What I am trying to get is to have a
heterogeneous network act (for mail purposes) as if it were a single
machine.  Here are my objectives, in order of importance:

	* Users should be able to send mail within the local network
	without knowing which anything about which machine each user
	lives on.  Alias files seem to solve this nicely.

	* Notification:  Users should be informed as soon as possible
	after mail arrives for them even if they are not logged into
	their "home" machine.

	* Distributed access: Users should be able to read their mail
	from whatever machine they happen to be logged into, rather than
	having to log into their "home" machine to read mail.

	* Centralized administration:  Ideally, it should be possible to
	add users from a single machine.

It may be that Sendmail is not capable of providing the functionality I
want in a heterogeneous environment.  Still, I want to get as much of
this agenda implemented as possible.

One place I am fairly sure I can get to is notification without
distributed access.  It seems to me that if I export the /var/spool/mail
directory under a different name to each of the client machines, I can
get the mail notifiers on the client machines to tell the user that he
has mail on the central mail machine.  Then the user would just have to
log in to his home machine to pick up his mail.  I'd like to do better
if I could, though.

Mark H. Zellers
(415) 325-7175
decwrl.dec.com!voltaire!bwayne!mark

rickert@mp.cs.niu.edu (Neil Rickert) (12/17/90)

In article <1990Dec15.203420.25181@starnet.uucp> mzellers@starnet.UUCP (Mark Zellers) writes:
>In article <4386@alliant.Alliant.COM> rdr@cl4.alliant.com (Roger Roles) writes:
>>
>I'll try your suggestion re: the OR flag.  If I don't have multiple
>machines writing into a single spool directory, is there another way I
>can acheive the same effect?  What I am trying to get is to have a
>heterogeneous network act (for mail purposes) as if it were a single
>machine.  Here are my objectives, in order of importance:
>
>	* Users should be able to send mail within the local network
>	without knowing which anything about which machine each user
>	lives on.  Alias files seem to solve this nicely.
>
>	* Notification:  Users should be informed as soon as possible
>	after mail arrives for them even if they are not logged into
>	their "home" machine.
>
>	* Distributed access: Users should be able to read their mail
>	from whatever machine they happen to be logged into, rather than
>	having to log into their "home" machine to read mail.
>
>	* Centralized administration:  Ideally, it should be possible to
>	add users from a single machine.
>
>It may be that Sendmail is not capable of providing the functionality I
>want in a heterogeneous environment.  Still, I want to get as much of
>this agenda implemented as possible.
>
 You are asking too much of sendmail to expect it to do all of this.

 Sendmail is basically a mail transfer program.  It transfers messages from
one machine to another.

 In the usual scheme of things (in a BSD setup for example), when mail arrives,
sendmail invokes a local delivery agent (usually /bin/mail).  The local
delivery agent actually stores the mail in the mail box.

 Notification is usually done either by the shell (which periodically checks
the date of your mailbox), or by something like biff.  Biff works because the
delivery agent (/bin/mail) sends it a message that mail has been received.

If you are satisfied with shell notification, you can export the mail spool
directory.  The user CAN read the mail from any machine where it is mounted.
If you worry about NFS updates, you can always export/mount as read-only.  That
would allow reading the mail, but not deleting it, on machines other than the
home machine.

-- 
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115                                   +1-815-753-6940

fwp1@CC.MsState.Edu (Frank Peters) (12/17/90)

In article <1990Dec16.174928.2908@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes:
   >	* Users should be able to send mail within the local network
   >	without knowing which anything about which machine each user
   >	lives on.  Alias files seem to solve this nicely.
   >
   >	* Notification:  Users should be informed as soon as possible
   >	after mail arrives for them even if they are not logged into
   >	their "home" machine.
   >
   >	* Distributed access: Users should be able to read their mail
   >	from whatever machine they happen to be logged into, rather than
   >	having to log into their "home" machine to read mail.
   >
   >	* Centralized administration:  Ideally, it should be possible to
   >	add users from a single machine.
   >
   >It may be that Sendmail is not capable of providing the functionality I
   >want in a heterogeneous environment.  Still, I want to get as much of
   >this agenda implemented as possible.
   >
    You are asking too much of sendmail to expect it to do all of this.

Which is not to say you cannot HAVE all of this.  Point four isn't
really a mail issue at all.  It deals with things like yp or some
other distributed userid scheme.

We have mail NFS mounted on several machines of diverse type (suns,
sgis, mac/aux and probably a few others).  Mail from each machine is
passed to the central mail hub for delivery...even if it is an address
that appears to be local.  All outgoing mail has the same hostname
stuck on it.  This means that all replies are directed to the mail
hub.  If mail is mistakenly addressed to user@someclient.my.domain and
the MX record for that client is ignored then the client accepts the
mail and turns around and sends it on to the hub.  It means that a
user can send mail to his friend joe with the simple userid and ignore
the fact that the mail is never delivered locally and that joe is
reading mail on another client machine.  And the aliases file doesn't
enter into the picture.

Since the mail spool is NFS shared a user can read his mail on any
system.  And bif notifies of new mail on any system.  

The only mail updates the client does are mail reading.  We were
concerned about file locking between heterogenious systems but so far
we've seen no sign of problem from this.

One advantage to the central mail hub approach is that the sendmail.cf
files on client machines can be extremely simple and stagnant.  All
modifications and real intelligence are centralized in the hub's
configuration.

One disadvantage is that you put a bit more load on the hub machine
and pass some extra bits about.

FWP
--
--
Frank Peters   Internet:  fwp1@CC.MsState.Edu         Bitnet:  FWP1@MsState
               Phone:     (601)325-2942               FAX:     (601)325-8921