Remove leftover SendGrid references after the Brevo migration was completed:
- Delete TF `cloudflare_record.mail_domainkey` (TXT at `s1._domainkey`,
SendGrid-era DKIM, hidden behind the SendGrid CNAME but would re-emerge
once the CNAME is removed).
- Clean up commented-out `smtp.sendgrid.net` relayhost references and the
`# For sendgrid` comment on `sasl_passwd` in the mailserver module.
DNS records deleted out-of-band (not TF-managed):
- CF: `s1._domainkey CNAME` + `s2._domainkey CNAME` → sendgrid.net (manual entries)
- Technitium internal `viktorbarzin.me`: `em7107`, `s1._domainkey`,
`s2._domainkey` CNAMEs → sendgrid.net
Verified end-to-end mail flow unaffected (Brevo outbound + IMAP receive,
roundtrip 20.4s — identical to baseline). Active DKIM (`mail._domainkey`
local + `brevo1/brevo2._domainkey` Brevo) untouched.
Viktor Barzin
5258f09230