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Old June 28th 03, 08:08 AM
Paul
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In article , KenTak
wrote:

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I have checked with my ISP (Earthlink), and he finds no problems with that
particular server.
I use a pop server for incoming and smtp for outgoing.
Ken


My ISP made a change to our mail server, where ICMP was disabled (so
for example you cannot ping the server) and the MTU was changed to a
value which happened to be 10 or 20 bytes less than the MTU of my
router. This places the mail server in what I think is termed a
"black hole". What happens is, when you send a large email, the
email program sends full sized packets. Normally, TCP/IP would
"discover" the MTU of the destination, using a function supported
by ICMP. Something to do with whether to fragment the packet or
not. Unfortunately, the protocol is such, that a server operating
in a black hole, returns nothing to the sender, and the protocol
freezes, because there is no retry by your computer. When I phoned
tech support at my ISP, they were all sweet and innocent, explaining
it was my fault that my MTU was too big, and would I reduce it.
They didn't explain the change they made, which is normally
implemented as some kind of protection against security or denial
of service attacks on the mail server.

Now that I've reduced my MTU, everything is back to normal. I
hope tech support at Earthlink are more honest about what they
have done with their server. It is quite possible the lowest
tier individuals who answer the phone, know nothing of the details.

HTH,
Paul



Fawad Chughtai wrote:

Maybe there is a problem with your mail server, and not your computer?
So you are using a pop server to send email?

-Fawad

On Fri, 27 Jun 2003, KenTak wrote:



I am not able to send attachments by e-mail; I can receive them.
I have P4PE with XP Pro installed; firewall disabled.
I've tried Netscape 7.02, Mozilla 1.3, and Outlook 98;
none have been able to send attachments.
I've tried small and large files.

Thanks for any help
Ken









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!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
html
head
meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"
title/title
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body
I have checked with my ISP (Earthlink), and he finds no problems with that
br
particular server.br
I use a pop server for incoming and smtp for outgoing.br
Kenbr
br
Fawad Chughtai wrote:br
blockquote type="cite"
"
pre wrap=""Maybe there is a problem with your mail server, and not

your computer?
So you are using a pop server to send email?

-Fawad

On Fri, 27 Jun 2003, KenTak wrote:

/pre
blockquote type="cite"
pre wrap=""I am not able to send attachments by e-mail; I can

receive them.
I have P4PE with XP Pro installed; firewall disabled.
I've tried Netscape 7.02, Mozilla 1.3, and Outlook 98;
none have been able to send attachments.
I've tried small and large files.

Thanks for any help
Ken


/pre
/blockquote
pre wrap=""!----
/pre
/blockquote
br
/body
/html

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