Re: Yahoo Mail Delivery Issues

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Hi Ralph

Doing some kind of load balancing based on DNS and the geographical =
location is perfectly fine.
I would probably also setup an anycast DNS system if our environment =
would be as big as Yahoo=E2=80=99s.

But I would definitely be making sure that all records my servers =
respond with are listening for the service in question.
That means in this case: All A or AAAA records =E2=80=9Creferenced" by =
an MX entry should at least accept SMTP connections on port 25.

Or how is one supposed to deliver mails otherwise ;-) ?

Cheers,
Dominic





> On 16 Sep 2019, at 20:26, Ralph Kr=C3=A4mer <[email protected]> =
wrote:
>=20
> Hi Dominic,
>=20
> what's wrong with that?
>=20
> global operating companies do that for a good reason.
>=20
> they use geoIP on your client address to figure out the nearest server =
for you and put it into the reply to your request.
>=20
> you will be able to connect with much less latency than connecting to =
another server on another continent
>=20
> sometimes dns is also used to achive some kind of loadbalancing - just =
to keep in mind ;-)
>=20
> cheers
>=20
> Ralph
>=20
> ----- Am 16. Sep 2019 um 15:51 schrieb Dominic Schlegel =
[email protected]:
>=20
>> Hi All
>>=20
>> We are experiencing problems delivering mails for domains having =
their MX record
>> set to mx-eu.mail.am0.yahoodns.net (for example yahoo.it, yahoo.de,
>> yahoo.co.uk). So far we have figured out that Yahoo=E2=80=99s DNS =
servers send
>> different responses. Depending on the DNS response we are able to =
establish
>> SMTP connections. Below example shows 2 servers from their DNS that =
seems to
>> accept SMTP connections:
>>=20
>> [root@x1:~] # dig a mx-eu.mail.am0.yahoodns.net @yf2.yahoo.com +short
>> 188.125.72.73
>> 188.125.72.74
>>=20
>> [root@x1:~] # telnet 188.125.72.73 25
>> Trying 188.125.72.73...
>> Connected to mtaproxy1.free.mail.vip.ir2.yahoo.com.
>>=20
>> [root@x1:~] # telnet 188.125.72.74 25
>> Trying 188.125.72.74...
>> Connected to mtaproxy2.free.mail.vip.ir2.yahoo.com.
>>=20
>> On the other hand we sometimes get other replies from the =E2=80=9Csame=
=E2=80=9D (the id.server
>> chaos record tell=E2=80=99s us it=E2=80=99s a different one) DNS =
server with different A
>> records that do not accept SMTP connections:
>>=20
>> [root@x1:~] # dig a mx-eu.mail.am0.yahoodns.net  @yf2.yahoo.com =
+short
>> 188.125.73.87
>> 212.82.101.46
>>=20
>> [root@x1:~] # telnet 188.125.73.87 25
>> Trying 188.125.73.87...
>> telnet: connect to address 188.125.73.87: Operation timed out
>> telnet: Unable to connect to remote host
>>=20
>> [root@x1:~] # telnet 212.82.101.46 25
>> Trying 212.82.101.46...
>> telnet: connect to address 212.82.101.46: Operation timed out
>> telnet: Unable to connect to remote host
>>=20
>>=20
>> We have so far confirmed this behaviour from different AS (Hetzer, =
OVH). Does
>> anybody else experiencing the same behaviour?
>>=20
>> We have tried to contact their postmaster address and few others we =
found on the
>> internet. Unfortunately so far no one was really able to help us. The =
Yahoo
>> Small Business Phone Number that has been posted on this list back in =
October
>> 2009 seems no longer to be in operations too. Therefore if you know =
how to get
>> in touch with their technical staff that would be much appreciated.
>>=20
>>=20
>> Best Regards
>> Dominic Schlegel
>>=20
>>=20
>>=20
>> _______________________________________________
>> swinog mailing list
>> [email protected]
>> http://lists.swinog.ch/cgi-bin/mailman/listinfo/swinog
>=20


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