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Re: Yahoo! Mail Issue
From: Matthew Petach <mpetach () netflight com>
Date: Tue, 12 Apr 2011 00:33:05 -0700

On Tue, Apr 12, 2011 at 12:12 AM, Nathanael C. Cariaga
<nccariaga () stluke com ph> wrote:
Strangely though I noticed that the email accounts that seems to be affected
by our concern seems to be related to the Yahoo SG servers.....

Oh.  You don't seem to want to accept connections from the singapore
servers at all:

-bash-3.2$ telnet qc.stluke.com.ph 25
Connected to qc.stluke.com.ph.
Escape character is '^]'.
550 Blacklisted: Blocked - see http://www.spamcop.net/bl.shtml?
Connection closed by foreign host.

So, they really can't send mail to your users--but it's your machine
rejecting the connection.  :/


On 4/12/2011 3:04 PM, Christopher Balmain wrote:

We had a lot of issues delivering mail to yahoo.com.sg about a year ago
(just the .sg domain, plain .com was fine). Could establish connection
but it'd die halfway through transferring mail. A static route to drop
the MTU (for their subnet only) to 1000 fixed the problem right up.

Not sure if pmtud was/is broken or what.

- Chris

On Tue, 2011-04-12 at 15:29 +1000, Nathanael C. Cariaga wrote:

Thanks anyway.  I just find this issue intriguing since not all Yahoo
mail accounts are affected.  In addition, incoming mails from other
domain doesn't seem to be affected.  That is why I want to check if it
is a network issue :)


On 4/12/2011 1:17 PM, Matthew Petach wrote:

On Mon, Apr 11, 2011 at 9:54 PM, Brielle Bruns<bruns () 2mbit com>   wrote:

On 4/11/11 10:47 PM, Matthew Petach wrote:

mpetach () opstools1:~>     telnet 25
Connected to static-host-219-90-94-56.tri.ph.
Escape character is '^]'.
ehlo yahoo.com
554 SMTP synchronization error
Connection closed by foreign host.
mpetach () opstools1:~>

I imagine when port 25 stops giving 5xx
failure message back, mail reception
might improve.   ^_^;

Works fine for me, your getting an error because your trying to send a
command before receiving the first 220, aka RFC violation.  As long as
connect, wait a moment without trying to send a command, your fine.


See, that's what happens when you ask networking people
to try to troubleshoot mail issues.  ^_^;;

Sorry about that.  :(


Nathanael C. Cariaga
Network & Security Administrator
St Luke's Medical Center

Tel (QC) :  +63 2 723 0101 ext 5520 / 4206
Tel (GC) :  +63 2 789 7700 ext 6035 / 6036
Tel      :  +63 2 356 5686
Mobile   :  +63 922 8735686
EMail    :  nccariaga () stluke com ph

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