the mail trail...sendmail

[Alexander Dalloz]

Am Mo, den 28.03.2005 schrieb rado um 16:44:

> Oh, I am guilty of running programs that I don't know exactly what
> they/their job is in the total process.
> I'm talking about the mail system I have set up.
> I just have a basic sendmail/procmail/evolution pop setup.
> I want to know exactly what sendmail's job is. The man sendmail page
> says it's job is to sendmail, as the name implies. Please tell me if my
> thinking is warped. I think sendmail sends the mail in both directions.
> you write a msg, it goes to sendmail and it gets sent on the way. 
> a msg comes in sendmail is listening on, think it's port 25. sendmail
> grabs it and.....

http://sial.org/howto/sendmail/

There you find some good documentation and even illustration.

> Here is where I am hung up. What actually takes place now? 

Sendmail is only an MTA (Mail Transfer Agent). It does not care itself
for mail storage.

> In just a basic, Sendmail system w/out many changes at all that came
> stock w/FC3, can I assume that: Say a msg comes in for rado, does it go
> to var/spool/mail/rado? 

Correct. And this is the case because Procmail is configured to be the
local delivery agent (LDA).
 
> when exactly does procmail get in the game?

As soon as Sendmail wants to pass the mail over to the LDA.
An alternate can be to let Sendmail pass the mail over to the mail
storage / mail access server - for instance Cyrus-IMAPd which comes too
with Fedora Core - by using LMTP. This is a protocol very similar to
SMTP. LMTP stands for Local Mail Transmission Protocol. Instead, which
is the old way how Sendmail and Cyrus-IMAPd communicated, Sendmail could
use the deliver binary of Cyrus to pass the mail over to him. A third
way could be to use Sendmail -> Procmail -> (cyrus-)deliver ->
Cyrus-IMAPd's storage.

> I notice that in /home/rado there is lots of stuff concering mail.

Because /var/spool/mail/$USER is just the spool mbox for INCOMING. If
you run an IMAP and move mail over to a specific folder, then the mail
goes from INBOX /var/spool/mail/$USER by default to an mbox in
$HOME/<IMAP-folder-mbox-file>

> ~/Mail, ~/mail, ~/.evolution.

They should result from mail application usage. So with .evolution that
is obvious. I am not sure which application will store information in
~/Mail and which one in ~/mail. You may find out by just doing a content
listing in there.

> I really don't want to get too, too, tech here, just a little
> understanding of where the mail trail goes and how to follow it.

That is a fair approach.

> john rose

Alexander


-- 
Alexander Dalloz | Enger, Germany | GPG http://pgp.mit.edu 0xB366A773
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