On Thu, 9 Sep 1999, David Huybregts wrote:
> Hello all,
>
> Why should I use sendmail and / or why should I use smtp (I use kmail) to
> send / receive my email?
>
> I use a ppp-connection to my ISP.
> (I think ) I'm using sendmail right now, but root is getting all message
> back, because the recipients don't accept mail from a unknown domain
> (enterprise.universe)...
>
> I've heard that I have to use sendmail instead of smtp, because when I use
> smtp, I should be online, whenever I write a message... And I sure want to
> write some messages, when I'm not online (I type fast, but my thoughts are
> rather slow ;-)
>
> Don't tell me the rtfm, because I don't understand them (most of the
> time)... Just plain English, please...
>
David,
You are confused. SMTP (Simple Mail Transfer Protocol) is a
_protocol_ used for the transfer of mail. 'sendmail' is a _server_ for the
SMTP protocol.
On machines connected via dialup to the internet, the most common
way of receiving mail is via the POP (Post Office Protocol) protocol. A
pop-server is a server for this protocol. The POP protocol is very
different from the SMTP protocol and for the end-user, can only be used to
receive messages.
On dialup hosts, sending mail is _always_ done through SMTP. In
programs such as the Netscape mailer, there is a place where you can
specify the SMTP server that you are using. This needs to be the hostname
of the machine on which the SMTP server is running.
There are two ways of handling this : typically ISP's provide an
SMTP server which their users can use to send mail. If you use this, it
means that you should be connected to the internet when sending mail.
The alternative is to use your own mail server. Redhat, I believe,
comes equipped with a working configuration of 'sendmail' which will work
for dialup clients. Using this server means that you can send messages
when you are offline. However, this is an illusion only : the mail server
on your machine will queue up the messages for transmission across the
internet, and will transmit it only when you get connected.
I suspect that this is where your problem arises. A lot of mail
servers that receive messages try to resolve the envelope sender 'from'
header to see that it makes sense. If it doesnt, you get a bounce. When
sending through your ISP server, the ISP has already taken care to ensure
that said bounce doesnt occur. When doing it yourself, you need to rewrite
the header yourself.
There is no getting around reading TFM for this. If you have
problems understanding portions of the manual, ask questions and we will
try to answer. But I repeat, you need to rtfm : if you cant do your
homework, why should we do it for you?
Regards,
Kenneth
