Edit: Maybe it's a problem with your resolvers?
---
# dig mx hotmail.it
; <<>> DiG 9.3.4 <<>> mx hotmail.it
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1850
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 3, ADDITIONAL: 15
;; QUESTION SECTION:
;hotmail.it. IN MX
;; ANSWER SECTION:
hotmail.it. 86400 IN MX 5 mx2.hotmail.com.
hotmail.it. 86400 IN MX 5 mx3.hotmail.com.
hotmail.it. 86400 IN MX 5 mx4.hotmail.com.
hotmail.it. 86400 IN MX 5 mx1.hotmail.com.
;; AUTHORITY SECTION:
hotmail.it. 86399 IN NS ns1.msft.net.
hotmail.it. 86399 IN NS ns3.msft.net.
hotmail.it. 86399 IN NS ns4.msft.net.
;; ADDITIONAL SECTION:
mx1.hotmail.com. 3133 IN A 65.54.245.8
mx1.hotmail.com. 3133 IN A 65.54.244.8
mx1.hotmail.com. 3133 IN A 65.54.244.136
mx2.hotmail.com. 3133 IN A 65.54.244.40
mx2.hotmail.com. 3133 IN A 65.54.244.168
mx2.hotmail.com. 3133 IN A 65.54.245.40
mx3.hotmail.com. 3133 IN A 65.54.245.72
mx3.hotmail.com. 3133 IN A 65.54.244.72
mx3.hotmail.com. 3133 IN A 65.54.244.200
mx4.hotmail.com. 3133 IN A 65.54.244.232
mx4.hotmail.com. 3133 IN A 65.54.245.104
mx4.hotmail.com. 3133 IN A 65.54.244.104
ns1.msft.net. 172332 IN A 207.68.160.190
ns3.msft.net. 172332 IN A 213.199.161.77
ns4.msft.net. 172332 IN A 207.46.66.126