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> No, that's simply not how SMTP routing works. So you want some third party provider to be delivering mail on behalf of a domain for which they don't have eve

> No, that's simply not how SMTP routing works. So you want some third party provider to be delivering mail on behalf of a domain for which they don't have even have the basics like DKIM and SPF set up, and hope for better deliverability than you could easily obtain with your own server?

kazinator 2y ago
Umm, no. The SPF and DKIM is something you set up in your DNS records, not they. Your SPF record, created by you, indicates that the certain forwarding servers you have chosen are authorized to deliver mail for your domain. When you change SMTP providers, you update that. E.g. a year ago I switched from Shaw to Novus (two Canadian service providers). I edited my server's SMTP credentials to the new Novus server and user ID, password and changed the SPF record to bless Novus servers as being my delivery agents. That's it; mail was flowing through thew new configuration. The ISP doesn't know anything about my domain or any of its DNS records. Yes, they have better deliverability than I could obtain with my own server directly, because my server is on a dynamic subscriber IP which makes it a pariah in the world of mail delivery. Sending from it directly to mail exchangers world over is a nonstarter. I could pay for some server in a cloud data center somewhere. What for? I have no issues with mail delivery.
- 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 ago
    SPF 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.

kazinator 2y ago

Umm, no. The SPF and DKIM is something you set up in your DNS records, not they. Your SPF record, created by you, indicates that the certain forwarding servers you have chosen are authorized to deliver mail for your domain. When you change SMTP providers, you update that. E.g. a year ago I switched from Shaw to Novus (two Canadian service providers). I edited my server's SMTP credentials to the new Novus server and user ID, password and changed the SPF record to bless Novus servers as being my delivery agents. That's it; mail was flowing through thew new configuration. The ISP doesn't know anything about my domain or any of its DNS records. Yes, they have better deliverability than I could obtain with my own server directly, because my server is on a dynamic subscriber IP which makes it a pariah in the world of mail delivery. Sending from it directly to mail exchangers world over is a nonstarter. I could pay for some server in a cloud data center somewhere. What for? I have no issues with mail delivery.

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 ago
  SPF 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.