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Ok, SPF could work if your provider has a fixed and published ip range for its outgoing mail servers. (Is that common?) DKIM though.. ? But I get your point:
by vanviegen 2y ago
Ok, SPF could work if your provider has a fixed and published ip range for its outgoing mail servers. (Is that common?)
DKIM though.. ?
But I get your point: it might beat a home server on a dynamic IP on deliverability. Both options seem troublesome.
- kazinator 2y agoSPF records have flexibility. It's possible to specify a domain name. Then any host which has an A record under that domain will pass. In my SPF record I have novus.ca. So I don't care what IP addresses Novus's mail servers use, as long as they identify as <host>.novus.ca. DKIM-signed messages can pass through SMTP hops. I'm not briefed up on the details of DKIM, but to my best current understanding, the originating domain signs the body and certain headers (not all of them) with its private key. When the message passes through multiple SMTP hops, some headers get added, like "Received: ...". I believe, these headers do not invalidate the DKIM signature. The relays just cannot be messing with the body of the e-mail, Subject:, From:, Date: and such. SMTP relay is not like a mailing list repost. I'm now looking at some raw e-mails with DKIM signatures. It looks as if the signatures plainly specify the names of headers that are included in the signature, via a field that starts with h=, listing colon-separated header names.