Hey,
I was debugging delivery issues from our freemail service to
outlook.com, since a big chunk of outbound messages currently get hard
bounce with status "530 5.7.57 Client not authenticated to send mail.."
=>
$host -t MX outlook.com
outlook.com mail is handled by 5 outlook-com.olc.protection.outlook.com.
Which is handled by name servers:
$host -t NS olc.protection.outlook.com
olc.protection.outlook.com name server ns2-gtm.glbdns.o365filtering.com.
olc.protection.outlook.com name server ns1-gtm.glbdns.o365filtering.com.
And if you ask these directly to eliminate local caches you RANDOMLY get
two sets of A servers:
First one is fine and accept messages:
$host -t A outlook-com.olc.protection.outlook.com
ns1-gtm.glbdns.o365filtering.com. | head -n 20
Using domain server:
Name: ns1-gtm.glbdns.o365filtering.com.
Address: 104.47.124.8#53
Aliases:
outlook-com.olc.protection.outlook.com has address 104.47.18.161
outlook-com.olc.protection.outlook.com has address 104.47.22.161
The other one seems to contain relay servers requiring AUTH:
$host -t A outlook-com.olc.protection.outlook.com
ns1-gtm.glbdns.o365filtering.com. | head -n 20
Using domain server:
Name: ns1-gtm.glbdns.o365filtering.com.
Address: 104.47.124.8#53
Aliases:
outlook-com.olc.protection.outlook.com has address 52.101.42.11
outlook-com.olc.protection.outlook.com has address 52.101.40.30
outlook-com.olc.protection.outlook.com has address 52.101.9.15
outlook-com.olc.protection.outlook.com has address 52.101.8.47
outlook-com.olc.protection.outlook.com has address 52.101.8.45
outlook-com.olc.protection.outlook.com has address 52.101.73.18
outlook-com.olc.protection.outlook.com has address 52.101.8.43
outlook-com.olc.protection.outlook.com has address 52.101.8.37
outlook-com.olc.protection.outlook.com has address 52.101.8.35
outlook-com.olc.protection.outlook.com has address 52.101.137.1
outlook-com.olc.protection.outlook.com has address 52.101.73.10
outlook-com.olc.protection.outlook.com has address 52.101.73.9
outlook-com.olc.protection.outlook.com has address 52.101.68.17
outlook-com.olc.protection.outlook.com has address 52.101.68.19
outlook-com.olc.protection.outlook.com has address 52.101.68.33
You can try it for yourself:
$while true; do host -t A outlook-com.olc.protection.outlook.com
ns1-gtm.glbdns.o365filtering.com | grep 'has address' | wc -l; sleep 1; done
2
2
2
2
2
2
2
2
2
2
2
2
2
2
56
2
2
2
2
2
56
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
56
56
2
56
2
2
2
2
^C%
It's not always DNS, but this time it is..
Best,
Tibor
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