I manage a VPS on Linode accessed through subdomain.example.com and I need to send email from this subdomain. I can't set any TXT records in Linode DNS manager because the name servers for example.com are something else, not ns1.linode.com, etc. So I need to ask someone who has access to example.com to add some records for me. How are TXT records for SPF and DKIM different if they are set in the domain dashboard for a subdomain?
SPF and DKIM records for a subdomain would only apply to emails with a from address of that subdomain, i.e. emails from
firstname.lastname@example.org. They'd be ignored entirely for email from