[lug] Sending e-Mail under Linux

[John Dollison]

Thanks for all the replies, that really helps.  I just finished reading
through some of the FAQ's at sendmail.org, and that helped, too.  It seems
like much of the newbie info is so broad and vague that it's of little use;
but the manpages and such are so complicated that (for now) they are way
over my head.  I feel stuck in the middle - I know enough to be dangerous
(or foolish), but not enough to be useful!  (Although I did know the diff
between POP & SMTP, I was just typing faster than my brain could think!)

One final question - I've heard that spammers could use my computer as a
mail-relay (something about telnetting via port 25?).  How can I detect
and/or prevent that from happening?  Or is that even a concern for a home
user?

Thanks again,
John



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----- Original Message -----
From: "Jeff Schroeder" <jeff at neobox.net>
To: <lug at lug.boulder.co.us>
Sent: Thursday, August 29, 2002 8:04 AM
Subject: Re: [lug] Sending e-Mail under Linux


John:

> 1.  After installing RedHat 7.3 on one of my computers, I opened
> KMail 1.4.1 and tried to send a test mail to my hotmail account,
> before I had actually configured KMail.  I expected it to act like a
> Windows machine (ok, shoot me) and say "You're not configured yet!",
> then open some sort of Wizard. Instead, it really did send a mail to
> my hotmail account, with the From: and ReplyTo: addresses set to
> <john at localhost.localdomain>.

That's because you've logged into the system as user "john", and your
hostname (by default) is "localhost.localdomain".  When you clicked
"send" in KMail, it used your local copy of Sendmail to fire off the
letter.  Sendmail resolved the Hotmail domain and successfully
delivered the message.

Note that replying to that message will fail, because Hotmail (and,
indeed, anyone "out there") won't be able to resolve
"localhost.localdomain" properly.  It'll resolve to their own machine,
if anything at all.

> 2.  After playing with KMail a little, I found that I could change
> the identity to simulate my wife's yahoo account, and even send an
> e-mail to a list she belongs to.  I don't understand how I managed to
> do this without some sort of authentication stopping me.  It seems
> like I could simulate anyone I wanted?

Absolutely.  Welcome to the world of spammers. ;)

While you can "impersonate" anyone by changing your From: or Reply-to:
addresses, remember that when someone responds to your message, it will
go to the address you've given.  So in this case, your wife will get
the responses-- not you.

> 3.  If I'm using sendmail to create my own custom e-mail addresses,
> how do I ensure any replies come back to me, short of setting my
> ReplyTo: address to my hotmail or AT&T accounts?

That's exactly what you must do.  See above.

> 4.  In Outlook Express, you could choose POP3, IMAP, or HTTP mail,
> but I didn't see that last option in KMail.  Although I've figured
> out how to configure KMail to use SMTP to get my AT&T mail, I haven't
> figured out yet if there's a way to use KMail to retrieve my Hotmail.

In KMail, go to Settings > Configure KMail and click on the Servers
icon.  There you can set your Receiving and Sending mail server
properties.

Please note that you don't use SMTP to *get* mail; it's used for
*sending* mail.  POP3 and IMAP are used for retrieving mail, and HTTP
is typically a front-end to an IMAP server.

While I don't know how Hotmail works-- as far as whether it allows you
to use POP3/IMAP-- you can go to the Receiving tab and click Add to add
a mail server.  That's how you'd set up your AT&T mail account.  Note
that KMail supports multiple accounts, too.

> I hope these questions aren't too amateurish; but even a few pointers
> in the right direction would be greatly appreciated!  Thanks!

IMHO, e-mail is anything but amateurish.  There's a lot of stuff to
learn, and these are good questions to start with.  Hopefully you'll be
able to set everything up properly, and enjoy KMail (it's my mail
program of choice too).

HTH,
Jeff
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