I am probably one of the few people that use mailing list mode feature, but it seems e-mails from this discourse forum have stopped in November 2025.
Upon initiating the confirmation e-mail process, I observe this messages in logs:
Jan 24 16:08:02 mail bash[487454]: mail-1 | 2026-01-24T16:08:02Z INFO SMTP EHLO command (smtp.ehlo) listenerId = "smtp", localPort = 25, remoteIp = 185.105.252.151, remotePort = 58588, domain = "mail.nixosdiscourse.fcio.net"
Jan 24 16:08:02 mail bash[487454]: mail-1 | 2026-01-24T16:08:02Z INFO SPF EHLO check failed (smtp.spf-ehlo-fail) listenerId = "smtp", localPort = 25, remoteIp = 185.105.252.151, remotePort = 58588, domain = "mail.nixosdiscourse.fcio.net", result = No SPF record (spf.none), elapsed = 36ms
Confirmed with:
$ dig TXT mail.nixosdiscourse.fcio.net
; <<>> DiG 9.20.17 <<>> TXT mail.nixosdiscourse.fcio.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19711
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;mail.nixosdiscourse.fcio.net. IN TXT
;; AUTHORITY SECTION:
fcio.net. 300 IN SOA ns3.fcio.net. support.flyingcircus.io. 1723719336 10800 60 1209600 300
It’s defined in discourse.nixos.org:
$ dig TXT discourse.nixos.org
; <<>> DiG 9.20.17 <<>> TXT discourse.nixos.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17780
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;discourse.nixos.org. IN TXT
;; ANSWER SECTION:
discourse.nixos.org. 3200 IN TXT "v=spf1 ip4:185.105.252.151 ip6:2a02:248:101:62::1479 -all"
;; Query time: 13 msec
;; SERVER: 100.100.100.100#53(100.100.100.100) (UDP)
;; WHEN: Sat Jan 24 10:30:47 CST 2026
;; MSG SIZE rcvd: 118
But not on the DNS name returned by MX on discourse.nixos.org:
$ dig MX discourse.nixos.org
; <<>> DiG 9.20.17 <<>> MX discourse.nixos.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29906
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;discourse.nixos.org. IN MX
;; ANSWER SECTION:
discourse.nixos.org. 2314 IN MX 10 mail.nixosdiscourse.fcio.net.
;; Query time: 13 msec
;; SERVER: 100.100.100.100#53(100.100.100.100) (UDP)
;; WHEN: Sat Jan 24 10:31:46 CST 2026
;; MSG SIZE rcvd: 92