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’s.
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 “referenced" 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 Krämer <[email protected]> wrote: > > Hi Dominic, > > what's wrong with that? > > global operating companies do that for a good reason. > > they use geoIP on your client address to figure out the nearest server for > you and put it into the reply to your request. > > you will be able to connect with much less latency than connecting to another > server on another continent > > sometimes dns is also used to achive some kind of loadbalancing - just to > keep in mind ;-) > > cheers > > Ralph > > ----- Am 16. Sep 2019 um 15:51 schrieb Dominic Schlegel > [email protected]: > >> Hi All >> >> 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’s 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: >> >> [root@x1:~] # dig a mx-eu.mail.am0.yahoodns.net @yf2.yahoo.com +short >> 188.125.72.73 >> 188.125.72.74 >> >> [root@x1:~] # telnet 188.125.72.73 25 >> Trying 188.125.72.73... >> Connected to mtaproxy1.free.mail.vip.ir2.yahoo.com. >> >> [root@x1:~] # telnet 188.125.72.74 25 >> Trying 188.125.72.74... >> Connected to mtaproxy2.free.mail.vip.ir2.yahoo.com. >> >> On the other hand we sometimes get other replies from the “same” (the >> id.server >> chaos record tell’s us it’s a different one) DNS server with different A >> records that do not accept SMTP connections: >> >> [root@x1:~] # dig a mx-eu.mail.am0.yahoodns.net @yf2.yahoo.com +short >> 188.125.73.87 >> 212.82.101.46 >> >> [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 >> >> [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 >> >> >> We have so far confirmed this behaviour from different AS (Hetzer, OVH). Does >> anybody else experiencing the same behaviour? >> >> 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. >> >> >> Best Regards >> Dominic Schlegel >> >> >> >> _______________________________________________ >> swinog mailing list >> [email protected] >> http://lists.swinog.ch/cgi-bin/mailman/listinfo/swinog >
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