daniel@optepr0n:~$ for i in 25 993; do nc -z -v -w 8 mail.opensourcerers.net $i; done
nc: getaddrinfo for host "mail.opensourcerers.net" port 25: Temporary failure in name resolution
nc: getaddrinfo for host "mail.opensourcerers.net" port 993: Temporary failure in name resolution
daniel@optepr0n:~$ dig mail.opensourcerers.net

; <<>> DiG 9.11.25 <<>> mail.opensourcerers.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 58186
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;mail.opensourcerers.net.	IN	A

;; ANSWER SECTION:
mail.opensourcerers.net. 0	IN	CNAME	mx0.opensourcerers.net.
mx0.opensourcerers.net.	0	IN	A	91.109.244.9

;; Query time: 2859 msec
;; SERVER: fdc5:acbd:5ab1:d9c6:215:17ff:fedc:63e1#53(fdc5:acbd:5ab1:d9c6:215:17ff:fedc:63e1)
;; WHEN: Wed Feb 24 19:20:39 EST 2021
;; MSG SIZE  rcvd: 86

daniel@optepr0n:~$ dig mail.opensourcerers.net MX

; <<>> DiG 9.11.25 <<>> mail.opensourcerers.net MX
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 4236
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;mail.opensourcerers.net.	IN	MX

;; Query time: 2669 msec
;; SERVER: fdc5:acbd:5ab1:d9c6:215:17ff:fedc:63e1#53(fdc5:acbd:5ab1:d9c6:215:17ff:fedc:63e1)
;; WHEN: Wed Feb 24 19:23:45 EST 2021
;; MSG SIZE  rcvd: 52