Re: Testing email connection to the outside world

[Scott Klement <klemscot@xxxxxxxxxxxx>]

Comments in-line.

On Mon, 31 Dec 2001 rob@dekko.com wrote:
>
> We thought of bouncing it off of yahoo or hotmail but the turnaround is
> unacceptable.  Yahoo has an out of office but I am not sure how often it
> grinds out the out-of-office message.  Yahoo also has a forwarding to
> another address which sounds really cool but that only pumps it out on
> occasion and not upon the receipt of new mail.
>

This would be a good test, but as you've noticed, the turnaround isn't
so hot.

> Our Cisco kid have me this url to verify our email, but I don't know how to
> utilize this information programmatically:
> http://www.zmailer.org/mxverify-cgi.html

That's nice.  I can show you how to do that programmatically -- but
it doesn't test everything.   It tests that the MX hosts that your ISP
has set up for you are receiving mail.  It does not eliminate any bugs
in those mail servers that might prevent the mail from actually getting
to you.  (Though, if you wrote your own version of these scripts, you
could have it create an actual message that gets sent to you, which
would be a more thorough test.)  Plus, it doesn't test outgoing mail at
all.

If you do want to do this programmatically, you'll need to make a choice:

   1) Do you want to call the existing mxverify-cgi scripts at zmailer.org
        and/or funet.fi.  (Presumably, they wouldn't mind you doing this?)

   2) Do you want to write a program that does the same thing that these
        scripts are doing, and run it from your AS/400?

Option #1 would be very easy using my new open-source "HTTP API".  (Which
allows you to communicate with web servers, cgi scripts, etc from an ILE
program, using GET or POST methods, and with & without SSL)  If that
interests you, take a look at:
    http://klement.dstorm.net/httpapi/

and let me know and I'll post a quick example of making such a query.  (I
wrote one in about 3 minutes, just to see if it would work)

For #2, you'd want to:
   1) Get the DNS MX records of your mail servers.  I posted an example of
         this here:
         http://archive.midrange.com/midrange-l/200110/msg01567.html
   2) Make TCP socket connections to each mail server and send the SMTP
         messages that look something like this:
              HELO whatever
              get back SMTP reply
              MAIL FROM:<>
              get back SMTP reply
              RCPT TO:<postmaster@that.domain>
              get back SMTP reply
              RCPT TO:<your.address@that.domain>
              get back SMTP reply

      For details on the sockets part, you can see my sockets tutorial
      at:   http://klement.dstorm.net/rpg/socktut/

      and for details on the SMTP protocol, see RFC 821

Or I could post a simple example of this, if this is indeed what you want
to do..

> Perhaps an option is to get DSL set up to my home and have a throwaway box
> there configured with it's own email domain to bounce back messages.  Work
> has already supplied my home PC and is currently paying for my second phone
> line.  Some other employees here have this DSL connection with a VPN.  We
> might be able to utilize them instead.

Even better would be a mail server that does not have any sort of VPN
connection to you that you could send a message to and have it mail back
a reply.,,