[ydl-gen] Re: Setting up sendmail to send mail (via SMTP)

[Eric Dunbar]

On 17/08/06, pstreibig <pstreibig at bcj.com> wrote:
> Eric Dunbar wrote:
> > On 16/08/06, Eric Dunbar <eric.dunbar at gmail.com> wrote:
> >> Hello all, I'm trying to make my server a little more user-friendly
> >> for my
> >> friends and for that to  happen I need to add the ability for the
> >> server to
> >> SEND mail.
> >>
> >> My ISP (Bell Sympatico) blocks all attempts to deliver mail directly to
> >> another mail server. The only way for me to get mail out is by
> >> connecting to
> >> my ISP's mail SMTP mail server using a username and password, over SSL.
> >>
> >> Does anyone have any idea how to set sendmail (or another MTA) up on
> >> YDL to
> >> send mail from the server (a Gallery installation, to be specific) to a
> >> public internet address?
> >>
> >
> > Well, I managed to answer my own question by stumbling on the right
> > web page at sendmail's site:
> > <http://www.sendmail.org/~ca/email/auth.html> under the section 'Using
> > sendmail as a client with AUTH'.
> >
> > On a hunch I changed an extra setting alongside the preferences
> > settings. Using the Webmin sendmail interface I made the following
> > additional change:
> >
> > Change #1 (not listed at page cited above):
> > "Send outgoing mail via host" is now set to my ISP's mail server (in
> > my case: smtphm.sympatico.ca

> DANGER!
> Be extra careful here with your sendmail settings once you implement
> this. Unless you are locking down access to your sendmail (for your
> friends) you could be creating an open relay.  This could be considered
> a breach of contact by your ISP, and cause other nastiness such as bots
> relaying spam through your authenticated to ISP connection.

It's not actually meant to relay mail for any users. Its only reason
for existing is to allow the gallery 1 and gallery 2
(http://gallery.menalto.com/) installations on the server to send
outbound e-mail.  I'm fairly sure that external e-mail relaying is
disabled since a "telnet serverIPaddress 25" says connection refused
and the sendmail 'SMTP port options' are set to
'Port=smtp,Addr=127.0.0.1, Name=MTA' (From Webmin help: This option
allows you to configure what IP address and port the sendmail server
listens on.).

Besides, the router does not relay any inbound 'port 25' requests to
the server so someone outside the local network would be unable to get
to the server via that port anyway.

> That being said, I believe sendmail reads it's configs the same way
> postfix does (which i am familiar with using).  If this is the case,
> then having a duplicate entry should not matter.  Grouping your changes
> at the end of the config will make your life easier than having to
> search throughout the entire config file.  Just for your own sanity you
> should note why you made the changes.

Notes made :-)

> I'm curious though, when you say your ISP blocks all outbound mail.  How
> are they implementing this?  I guess it's more academic curiosity, but
> did you try changing the default port for sendmail?  There are more
> reasons for not doing this than for doing it though, not the least of
> which being the pain of maintaining an up to date, fully patched secure
> mail server, which ideally your ISP is doing for you already.

See Chris Murtagh's email for an succinct answer to your question.