Postfix and sendmail

[patrickbeyer]

Can anyone please advise me where I can find a good, and easy to follow tutorial or howto for Postfix and sendmail, on SUSE 10.1?

[Lakshmipathi]

Good one:

Quick HOWTO : Ch21 : Configuring Linux Mail Servers - Linux Home Networking

How to set up a mail server on a GNU / Linux system

Bad one : written me

--------------------------------------------------------------
> How to Send mail using Sendmail???
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>      ----An Incomplete and unreliable guide about sendmail---
> -------------------------------------------------------------
> Hi all,
> I want to share some points which are typed by myself (as cut - paste
> not working on some PDF files ;-)).
> Remember sendmail is a one big big program --probably you will never
> know how it works completely.
> Let's try to get some basics about sendmail which might -just might give
> us the feeling of "i know a bit about sendmail"
> Let's start with a famous sendmail quote,
> 
>     "He who has never configured `sendmail.cf' has no courage. He who
> has configured
>     it more than once has no brain."
>      -- Unknown
> 
> What's mail ?
> ==============
> A program which copies data from one machine to another and appends this
> data to a specific file in the recepients machine.
> data contains 2 parts:
> ======================
> *)data that is specific to transport medium like sender address and
> receipt address.
> *)data that is not specific to transport medium like subject,date when
> it's sent which forms mail header.
> we have to follow some standard mail header format which is provided by
> RFC-822
> 
> Phase 1: How mail was delivered???
> =========================
> 
> First we have to compose the mail using MUA (i really hate these terms
> anyway that's how mail works.so lets see them first).
> what's MUA?
> ------------
> Mail User Agent:MUA is nothing but a program the user uses it to read
> mail which has been delivered to user mailbox file.and sends mail ( hand
> over the mail) to an MTA. ( yes we got another term to explain )
> so what's MTA?
> --------------
> MTA - M for mail and A for Agent ...what's remaining..T for (come on
> man...make a guess --  think about network and it's layer something you
> may have studied ...somewhere... sometime ...)
> ..no...ok...time's up.
> T for Transfer
> So it's Mail Transfer Agent -MTA (shhhhhhhh....)
> 
> MTA- Accepts message passed by MUA or another MTA and decides the
> delivery method.
> 
> 
> Let's combine MUA and MTA and see what's happening...
> 
> 
> We compose our mail using MUA (Programs like
> mail,mailx,Evolution/outlook)
> (just think of it as notepad for a moment)
> Once you say , "send" it hands what you composed to an MTA (yes our
> sendmail)
> 
> 
> Sendmail will be running on our machine at port 25 waiting for
> connections and messages.
> So MUA gives the message to MTA  send to specified mail address.
> In programming terms (just imagine this i'm not sure how it works
> internally) mail (client)program connects to (server)sendmail program
> passing this message.
> 
> 
> 
> 
> How sendmail works
> ===================
> sendmail implements the SMTP protocol for linux systems.
> It sends and receives SMTP mail for the system and it acts as an
> interface between the user's mail program and internet.
> Sendmail runs to 2 modes try typing this ,
> 
> //////////////////////////////////////////////////////////////////////////
> #ps -aux | grep sendmail
> 
> root      7527  0.0  0.3   7948  3172 ?        Ss   Oct03   0:00
> sendmail: accepting connections
> smmsp     7533  0.0  0.2   6968  2664 ?        Ss   Oct03   0:00
> sendmail: Queue runner@01:00:00 for /var/spool/clientmqueue
> ///////////////////////////////////////////////////////////////////////////
> 
> as you can see from the output there is 2 process is running for
> sendmail.
> one with process id 7527 says "accepting connection"
> and another with process id 7533 says "Queue runner"
> 
> 
> Mode 1:
> ======
> Real time mode for outbound mail delivery.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> When MUA has mail to send it creates an instance of sendmail program to
> deliver that pice of mail.This instance of sendmail lives long enough to
> deliver that one piece of mail.If it can't it successfully deliver the
> mail.It writes the mail to quque and terminates.
> Mode 2:
> ======
> Daemon mode for collecting inbound mail & quque processing.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Runs the entire time of the system is running...contantly listens for
> inbound mail & periodically processing the queue to deliver the
> undelivered mail.
> 
> Phase 2: How mail was delivered???
> =========================
> Once the mail was delivered to sendmail:Now the sendmail checks the "to
> address" part .
> append data locally :
> ====================
> If it's for local delivery then sendmail,check whether there is any
> aliasis for the given address if not just appends the contents to user's
> mailbox file else it forwards the mail to the specified destination.
> append data remotely:
> ====================
> To deliver mail message over network uses SMTP (no...we got another
> term ) which is given by RFC-821
> so what's is SMTP:
> (wait a second -- i do a quick google on it :-))
> SMTP is a protocol used to sent and receive mails.(where - a protocol is
> set of rules ..only thing i remember from my college's networking
> subjuct :-) )
> 
> 
> Some definitions that help us :
> 
> Mail server :
> A mail storage system.This server keeps all mail boxes
> in /var/spool/mail.
> 
> type ls  /var/spool/mail you can see users of your system
> 
> SMART HOST :
> * It manages transmission of mail across private firewall.
> Allows you to specify the host that should relay all outgoing mail that
> you are unable to deliver directly & the mail transport protocol to use
> to talk to it.
> 
> config. files info.
> 1)sendmail.mc : Macro file used to generate the original cf file.
>                 Use command : m4 sendmail.mc > sendmail.cf
> 2)aliases (aliases.db)
>         : Not so important file i guess.Just contains aliases for e-mail
> addresses.
>         : If you change this file , creat a new aliases.db .Just execute
>              newaliases at command prompt.
> 3)access  (access.db)
>         : Tells who can use the sendmail program.Allows you to configure which
> hosts or users you will accept mail from & which you will relay mail
> for.
> 
> 
> I think we reached end part ,i still got plenty doubts regarding how
> sendmail works(bind(),connect() ..how really it really works) It'll take
> few months to  learn it.
 ---------------------------->The  End<-----------------------------------------------

HTH

[patrickbeyer]

Thank you for the help

[Xorix]

You can goto HowtoForge - Linux Howtos and Tutorials | Howtos about Linux and Open Source. They have a lot of Howto's that might help you.