A
 B
 C
 D
 E
 F
 ⚖

i
B

B

A

C
D →
D →
B →
—
E →
F →
Proton

D

→

←

E

1
2
3
4

F

      ; mailboxes / buzones
@        MX     10 mx1.<provider>
@        TXT    "v=spf1 include:<provider> -all"
<sel>._domainkey  CNAME/TXT  (DKIM)
_dmarc   TXT    "v=DMARC1; p=none; rua=mailto:…"

; subdomains that never send / que nunca envían
web      TXT    "v=spf1 -all"

; mail records: DNS only (grey cloud)

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