My mails can't reach the mailing list because list.parabola.nu doesn't have a valid mail server:

# dig list.parabola.nu MX

; <<>> DiG 9.13.3 <<>> list.parabola.nu MX
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 58935
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 67bf51b186c1510d8dbe32e05bad782ae1f7163101dd3844 (good)
;; QUESTION SECTION:
;list.parabola.nu.        IN    MX

;; AUTHORITY SECTION:
parabola.nu.        10482    IN    SOA    ns1.he.net. hostmaster.he.net. 2018091800 10800 1800 604800 86400

;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 28 02:39:06 CEST 2018
;; MSG SIZE  rcvd: 130

However for some reasons parabola.nu does:

# dig parabola.nu MX

; <<>> DiG 9.13.3 <<>> parabola.nu MX
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61120
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: e49808efc2fe1b3336b8c1a75bad784590c4840d6c85ef97 (good)
;; QUESTION SECTION:
;parabola.nu.            IN    MX

;; ANSWER SECTION:
parabola.nu.        86259    IN    MX    0 winston.parabola.nu.

;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 28 02:39:33 CEST 2018
;; MSG SIZE  rcvd: 92