Mail for some reason is not delivering to outlook.com
Find your namservers.

#cat /etc/resolv.conf
nameserver 69.xx.xx.xx
nameserver 69.xx.xx.xx

– in this case the example is 69.xx.xx.xx

$ dig MX outlook.com @69.xx.xx.xx
; <<>> DiG 9.9.2-P2-RedHat-9.9.2-3.P2.el5 <<>> MX outlook.com @69.64.66.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 19033 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;outlook.com. IN MX ;; Query time: 2 msec ;; SERVER: 69.64.66.11#53(69.64.66.11) ;; WHEN: Fri Jan 9 15:38:48 2015 ;; MSG SIZE rcvd: 29 [/bash] There is no result. Now Change to google nameservers. (8.8.8.8 or 8.8.4.4 ) [bash] ~]$ dig MX outlook.com @8.8.8.8 ; <<>> DiG 9.9.2-P2-RedHat-9.9.2-3.P2.el5 <<>> MX outlook.com @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33959 ;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;outlook.com. IN MX ;; ANSWER SECTION: outlook.com. 17432 IN MX 10 mx3.hotmail.com. outlook.com. 17432 IN MX 10 mx4.hotmail.com. outlook.com. 17432 IN MX 10 mx1.hotmail.com. outlook.com. 17432 IN MX 10 mx2.hotmail.com. ;; Query time: 11 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Fri Jan 9 15:39:26 2015 ;; MSG SIZE rcvd: 128 [/bash]