Mail problem

Hello,

I have domain pismenica.rs. I configure mx as you pointed out in your tutorial. Dig returned this:

dig pismenica.rs MX

; <<>> DiG 9.9.3-rpz2+rl.13214.22-P2-Ubuntu-1:9.9.3.dfsg.P2-4ubuntu1.1 <<>> pismenica.rs MX
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10231
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 3

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;pismenica.rs.            IN    MX

;; ANSWER SECTION:
pismenica.rs.        3593    IN    MX    20 mx2.zoho.com.
pismenica.rs.        3593    IN    MX    10 mx.zoho.com.

;; AUTHORITY SECTION:
pismenica.rs.        3593    IN    NS    ns1.twisted4life.com.
pismenica.rs.        3593    IN    NS    ns.pismenica.rs.

;; ADDITIONAL SECTION:
ns.pismenica.rs.    3593    IN    A    148.251.152.74
ns1.twisted4life.com.    5972    IN    A    202.157.182.142

;; Query time: 1 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Wed Oct 28 13:35:29 CET 2015
;; MSG SIZE rcvd: 168

I can receive but cannot send mails.
Can you help me?

Thanks.