It would really help to know what the source IPs or source prefix these connections are coming from. It's entirely possible there's an old bogon filter entry lurking around or some such that's causing headaches. Thanks! Matt On Thu, Aug 16, 2012 at 10:18 AM, Georgios Vlachos <g.vlachos@kestrel-is.gr> wrote:

First thing we checked and fixed (in less than 24h) was the PTR record, I forgot to mention it....

-----Original Message----- From: Jim Ray [mailto:jim@neuse.net] Sent: Thursday, August 16, 2012 8:06 PM To: Georgios Vlachos Cc: nanog@nanog.org Subject: Re: yahoo admin mail contact (or answer)

Check reverse DNS. We had same problem with AOL.

Sent from my iPhone

On Aug 16, 2012, at 12:51 PM, "Georgios Vlachos" <g.vlachos@kestrel-is.gr> wrote:

...

Hello all,

We put into production a new mailserver 2 weeks ago, and we can send email to everybody (no complaints and testing) except yahoo!

All their mailservers reset the TCP connections, before SMTP even starts. This happens randomly on all their mta (look below). As a sequence almost half the email we send to yahoo stay in the queue for a day in our mailserver and then get discarded (with a connection died message).

We get the SYN, SYN-ACK, ACK normal handshake and then a TCP reset from their mailserver.

Any idea or off-list contact is very welcome.

From their website I could not find a way to email them.

C:\Windows\system32>dig yahoo.com MX

; <<>> DiG 9.3.2 <<>> yahoo.com MX

;; global options: printcmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 970

;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 24

;; QUESTION SECTION:

;yahoo.com. IN MX

;; ANSWER SECTION:

yahoo.com. 72 IN MX 1 mta6.am0.yahoodns.net.

yahoo.com. 72 IN MX 1 mta7.am0.yahoodns.net.

yahoo.com. 72 IN MX 1 mta5.am0.yahoodns.net.

;; ADDITIONAL SECTION:

mta6.am0.yahoodns.net. 141 IN A 66.196.118.34

mta6.am0.yahoodns.net. 141 IN A 66.196.118.36

mta6.am0.yahoodns.net. 141 IN A 67.195.168.230

mta6.am0.yahoodns.net. 141 IN A 98.136.217.202

mta6.am0.yahoodns.net. 141 IN A 98.139.54.60

mta6.am0.yahoodns.net. 141 IN A 66.94.237.64

mta6.am0.yahoodns.net. 141 IN A 66.94.237.139

mta6.am0.yahoodns.net. 141 IN A 66.94.238.147

mta7.am0.yahoodns.net. 289 IN A 98.139.54.60

mta7.am0.yahoodns.net. 289 IN A 66.94.236.34

mta7.am0.yahoodns.net. 289 IN A 66.94.237.64

mta7.am0.yahoodns.net. 289 IN A 66.196.118.33

mta7.am0.yahoodns.net. 289 IN A 66.196.118.35

mta7.am0.yahoodns.net. 289 IN A 67.195.168.230

mta7.am0.yahoodns.net. 289 IN A 98.136.216.26

mta7.am0.yahoodns.net. 289 IN A 98.136.217.202

mta5.am0.yahoodns.net. 185 IN A 66.196.118.35

mta5.am0.yahoodns.net. 185 IN A 66.196.118.36

mta5.am0.yahoodns.net. 185 IN A 98.136.216.25

mta5.am0.yahoodns.net. 185 IN A 98.136.216.26

mta5.am0.yahoodns.net. 185 IN A 98.136.217.202

mta5.am0.yahoodns.net. 185 IN A 66.94.236.34

mta5.am0.yahoodns.net. 185 IN A 66.94.238.147

mta5.am0.yahoodns.net. 185 IN A 66.196.118.34

Thank you,

Georgios Vlachos

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