On Mon, 3 Sep 2001, Tim Hamel wrote:

> Sorry, don't mean to start an argument or anything, just speaking from my
> experience.

No problem.  I try very hard not to sound like an arse, and usually fail
miserably, so please adjust your mental filters accordingly...  8-)

> The way I picture it is like this. AOL users who compose mail and hit send go
> to the SMTP servers via their proprietary crap. Then, when the mail bounces
> out of AOL's network via the SMTP server, it's all standard. In other words,
> you can't connect to AOL's SMTP servers, no matter what.

Welll....  I have not used AOL since we maintained a test account in '95,
but at that time, their client software did indeed use some sort of funky
proprietary protocol (as did everything else associated with AOL).  I have
no clue how the AOL client end of things are handled right now, but
nothing would surprise me about that...  NOTHING.

Having said that, though, let's agree on some semantics: If it's a
proprietary protocol, it's not SMTP.  SMTP (Simple Mail Transfer Protocol)
is the Internet standard, anything else - well, isn't SMTP.  So once the
mail needs to traverse the Internet, it's SMTP.  Within AOL's own systems,
it could be EBCDIC coded Navajo or ROT13 Swedish Chef bork filtered
Swahili, I dunno.

> I can't really explain their IP/DNS addressing as it's quite
> complicated. The only thing constant is their proxy server! Even their
> TCP/IP (you can connect to 'em via TCP/IP instead of dialing up which
> is what I do) connection server is "secure" in that its IP changes
> almost by the minute.

That's usually a side effect of a highly redundant round-robin or other
algorithm load balancing arrangement.  You have X number of IP addresses
in DNS for the same host name, and set a very short TTL (Time To Live) for
the zone.  This means the client does a DNS lookup often, and will get
some semi-random different answer every time.  This minimizes the impact
of a failed server and spreads traffic across X number of servers, and
allows you to take them in and out of service on short notice.  You can do
this with just DNS, or use something like F5's (http://www.f5.com/)
products.

> As for POP, I haven't investigated that. Would be nice if they opened up
> their POP servers so you can telnet in instead of using their web based
> stuff. Btw, I'm not the OP, the topic caught my eye because I too wanted to
> find out how to do SMTP/POP with AOL's servers.

Here again...  if you can telnet to port 110 and use POP3 commands, it's
POP, otherwise it's something else.  Most of the web based email setups
use SSL on port 443 so it can't be sniffed between the client and the
server.  Hotmail used to, but apparently now the new owners don't care
about the privacy of their uers.

> Regards,
>
> Tim Hamel

Have a great week!

Dale

>
> In a message dated 9/2/01 1:46:11 PM Pacific Daylight Time, dale@BOTKIN.ORG
> writes:
>
>
> > The server names are all you should need anyway, if you care about
> > standards.  As for the "currently active one", that would be whichever one
> > you are connected to... *ANY* hostname that shows up as an MX record with
> > nslookup is "currently active".  They have several SMTP servers active at
> > all times, partly for fault tolerance and partly due to the enormous
> > amount of mail being received for AOL members from SPAMmers (there's that
> > connection).  The concept of "THE mail server" (singluar) is pretty well
> > outdated for most enterprises.
> >
> > Where I work, we have more than one MX record, and each of those is a
> > virtual IP that connects to a load balancer, which directs the connection
> > to one of N number of SMTP servers behind it.  Redundancy on top of
> > redundancy, load balancing on top of load balancing.
> >
> > Another common practice is to have one set of servers for incoming mail
> > and another set for outgoing mail.  Your outgoing mail servers don't need
> > to be specifically designated as such, as do your incoming mail servers
> > using MX records.
> >
> > In short: Nslookup *will* get all mail servers that AOL wants to accept
> > incoming mail.  You may or may not be able to determins which are being
> > used for outgoing mail, probably not.  SPAM being sent to AOL addresses
> > will go through the inbound mail servers, determined by MX records in the
> > DNS system.  And if AOL uses a proprietary methods of sending mail, it's
> > only internally...  if they presented a nonstandard mail interface to the
> > rest of the world, the rest of the world would be unable to communicate
> > with AOL users.  Whether this is a bad thing or not is a determination
> > left up to the individual reader.
> >
> > I may not know a lot about much, but I do have some small degree of
> > passing familiarity with TCP/IP, DNS, mail and other Internet protocols.
> > Perhaps some clue as to what it is exactly you're trying to do would clear
> > up any remaining confusion.
> >
> > Dale
> >
>
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