On May 27, 2008, at 9:31 AM, Yersinia wrote:
A version of CE for wireless. My "regular" CE will PICK UP email
when my
iBook is connected on WiFi, but it won't SEND. Port 587 "supposedly"
fixes this (sorry, but I don't understand the actual mechanisms of how
wireless works so I can't explain it). I say Port 587 "supposedly"
works
because while that's its intention, I had mixed results with it. To
wit:
It actually has nothing at all to do with wireless.
Email is transfered between mail servers via the SMTP protocol (a
particular set of commands and data used for transferring email).
Email clients send email to servers using the same SMTP protocol.
SMTP works over port 25. All networking software uses "ports". A port
is basically a specific location in the network stream.
Due to spamming, many ISPs started blocking port 25 access to
anything other than their own server. They couple this with the need
for SMTP Authentication, and this essentially blocks all outbound
email from anyone connected to their network. THe only way to send
email is to authenticate to their server. This is fine for someone
that is a customer of theirs, but no good for someone that is
visiting or otherwise using the connection and lacks a way to
authenticate.
This is done this way, to prevent virus infected windows machines
from automatically sending spam, if they can't reach the target
servers, they can't send their payload (and to prevent deliberate
spam as well).
One way around this is by using the SMTP Submission port. This is an
alternate connection port for an email client to send mail to a
server. This uses port 587. Because virtually no spam is sent via
port 587, most ISPs do not block that port on outbound traffic. This
may or may not change in the future, but as port 587 connections are
supposed to always require authentication for all connections,
hopefully it will remain a safe haven for email sending. (normal SMTP
over port 25 does not, and should not, require authentication for any
email destined for local delivery, that is, any email addresses
handled by the SMTP server receiving the connection).
So the Port 587 version of Emailer simply changes emailer from
sending out email over port 25, to sending it out over port 587. If
you are a person that travels or otherwise regularly runs into ISPs
that block port 25 access, then the Port 587 version may be of help.
Use of the port 587 version of course assumes that the mail server
you are connecting to supports receiving email over port 587. Not all
mail servers do, although it is something that is starting to be
adopted more and more.
At WiFi hotspots, even with Port 587, I was still able to pick up
email
but not send any out. BUT, at my boyfriend's house last summer, he has
what he calls a "wireless dialup" ethernet setup running (don't ask
ME,
please!). On this "network" of his, I WAS able to both send and
pick up
email on the iBook using CE Port 587. I still consider Port 587 worth
keeping and I'm glad I have it, but I guess the only place I can
use it
is at my boyfriend's house.
The port 587 use will have no impact on the ability to receive email.
Inbound email with Emailer is done using the POP protocol, that works
over port 110 and is an entirely different system from the SMTP used
for outbound email.
As to why it won't always work when on the road, two things come to
mind. 1: the ISP you are connected to is also blocking port 587.
Unusual, but possible, and with public hotspots, I can see they may
still block it to be extra careful with blocking the sending of spam.
The other possibility is the mail server you are connecting to at
those times is refusing the connection. It could be due to the
authentication method you are using, or maybe you are changing mail
servers and the alternate one simply doesn't support port 587 at all.
As for "wireless dialup", if I had to guess, he simply has a wireless
access point connected to dialup internet service instead of
broadband. The original model Airport Base Station supported doing
this, it had a modem built in and could dial on network demand. I'm
sure there were other vendors that made similar hardware (I know
there were pleanty of dial on demand routers on the market, so I
don't see why some of them couldn't have had wireless built in, or
you could simply daisy chain the wireless access port to a dial on
demand router and get the same effect).
-chris
<www.mythtech.net>
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