"bnmohan via WindowsKB.com" wrote in message news:75d5283163971@uwe...
I think your second para was the problem/solution: my account with my
ISPs is
used only to access the Internet, and I do not use their servers for
Email.
My POP3 and SMTP servers are on my domain hosted elsewhere. I had
therefore
not even created the free email account that they provide. It appears
that
for traffic from non-registered EMAIL users, there is some sort of
access
control on how often port 25 is sought to be accessed via their
connection. I
created my free email account, and mail now goes through smoothly.
Now I have to watch that account.
I am not sure I get the logic and reasoning behind the setup at my
ISP.
Wonder if someone could take me around.

You are connecting to your ISP. They want you using their mail server
to track any spam abuse that gets reported to them. They can use their
logs to determine from the headers of the reported spam which account
was connected using what IP address when the spam got sent through their
mail server. If it doesn't come through their mail server then they
could still use the log to check up on who was using the sending IP
address if their customer was running their own mail server. Doesn't
sound like you are running a mail server on your own host which is
connected to your ISP.

Besides requiring that you connect via port 25 to *their* mail server,
the other anti-spam restriction is blocking their customers from sending
e-mails through a mail server that is off their domain. That is, you
are trying to connect your e-mail client to a mail server that is not on
their domain. For many ISPs, they won't allow this inbound connection
from some other domain, so you can't get to their domain from your
domain (I.e., they block inbound connects to their mail servers that
come from somewhere other than their own customers on their domain).
For your ISP, they may preempt that restriction and not let you get
across their network to connect to some off-domain mail server. So you
have mail servers that allow connects only by customers on the same
domain as the mail server, and you have ISPs that won't let you cross
their domain to connect to some off-domain mail server. It's all to
enforce tracking of who is sending what to nail the spam sources.

For those domains that do not permit off-domain connects *to* their mail
server, sometimes they will provide an alternate setup to connect to
them. For example, off-domain connections to my Comcast mail server
requires that I enable SSL connects and use port 995 instead of 110 for
POP3 and use port 465 instead of 25 for SMTP. There might be another
option required, too, like SPA. So the e-mail config I use at home
while on their network is not the same config when I am travelling and
have to come from off-domain to connect to their mail servers.

For those domains that do not permit you to cross over their network to
connect to some off-domain mail servers, they are blocking traffic from
entering their domain and then leaving it that uses port 25 (although
protocol analyzers could also be used so as not to simply rely on the
port number). To get around this, some mail servers let you use
non-standard ports to connect to their mail servers. That way, the
network you are crossing won't block your on port 25 because you are
using some other port number. SSL connects on 995 for POP3 and 465 for
SMTP are often used for this.

Since you are crossing your ISP's network to connect to an off-domain
mail server provided by e-mail provider that you choose to use, find out
what port configs they permit for off-domain connections (i.e., you are
coming into their domain from somewhere off their domain). Maybe they
permit SSL connects using non-standard port numbers, or maybe the use
the standard ports and rely on your login credentials to prove you are
their customer and are authenticated to use their resources. If you
can't connect using the standard ports to their mail server because your
ISP is blocking traffic over port 25, you'll have to use non-standard
ports.