RE: Which mail system?
On 19-Feb-99 Robert-Jan Kuijvenhoven wrote:
> I have installed Linux and now I would like to start sending and
> receiving mail. I would like to send and receive mail to the smtp
> server and from the pop server from my ISP. My computer is a
> stand-alone machine, so there is no local mail.
> What is, in my case, the best package for mailing?
> The book 'Running Linux' (O'Reilly) suggests using smail and elm, but I
> have the feeling smail is for setting up a mailserver. Which I don't
> need because I connect to my ISP's mailserver. I can use netscape for
> this, but I would appreciate a mail system a mail system that receives
> mail in the background, without me having to start X and netscape every
Be careful not to get confused here. I think, when you are using Netscape
to connect to your ISP's mailserver then you are in effect using it as a
browser which happens to be reading your mailbox on the ISP's mailserver,
much as it would read another URL or a newsgroup.
If you want to have mail handling facilities on your own machine, then
there are two aspects to deal with.
You need a "Mail User Agent" (MUA) like elm, pine, mutt, ... (which don't
need X) or my favourite (see below) XFMail (which only works in X). This
is the friendly interface you interact with when you compose, read or
administer mail messages.
Netscape can also function as an MUA (and of course needs X).
You also need a "Mail Transport Agent" (MTA) like smail, sendmail, exim
... This is the software which sits in the background and handles the
transmission of mail. For instance, when you finish composing a mail in
your MUA and "send" it, this really invokes MTA activity; the MTA sorts
out what headers to attach to the mail and stacks these, and the message
text, in the outgoing queue directory. Depending on your connectivity, it
may then immediately pick it up and open up a Mail transport dialogue with
your ISP's mail-router, thereby transmitting it, or will leave it hanging
until you have a connection open and then (perhaps under an explicit
command such as "mailq" which for both smail and sendmail starts the
"queue run" to send off all the batched mail to the ISP) send it out.
Netscape does not function as an MTA.
For receiving mail, if your ISP's mailhost knows about your IP address
at the time it receives a mail for you, it may try to transmit it to
your machine immediately (depending on configuration). More likely,
it will stack your incoming mail in your mailbox on the ISP's mailhost
and wait for an explicit mail-pulling exercise using popclient or
fetchmail which will invoke its popserver facility; your own machine
is responsible for starting up popclient or fetchmail.
Mail thus received by your machine is stored in the first instance in
your local "mailbox" file (/var/spool/mail/userid). Some MUAs handle this
mailbox directly (elm, pine, ... ); others (XFMail, ... ) copy it down
and split it into several files, one for each message, in your personal
Mail directory (/home/userid/Mail/... or -- for Netscape --
/home/userid/nsmail/...) and only after this can you "see" the mail in
the MUA. It is not a good idea to use different MUAs promiscuously,
because of these different mail-handling methods.
Again, depending on your connectivity, you may decide to program
popclient or fetchmail activity to happen at set intervals (as a cron
job) or when you deliberately decide to open up a connection.
As to choice between smail and sendmail: in terms of what they do and how
they are invoked, they are very similar (smail is deliberately designed
to be a "plugin replacement for sendmail"). However, there are some
differences of interface. The major difference between them is in the
organisation of their configuration files, sendmail's being much more
obscure. However, a modern Linux system should incorporate
straightforward s[end]mail configuration for standard purposes as part of
its system administration utilities.
Once you have you MUA and MTA set up on your own machine, then you can
read and write mail "in the background" whether or not you are connected
to your ISP. As I am doing at this moment.
Hope this helps,
E-Mail: (Ted Harding) <Ted.Harding@nessie.mcc.ac.uk>
Date: 19-Feb-99 Time: 14:45:06
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