On 14.01.23 11:02, Chris Green wrote:
>I use postfix on my home server and deliver mail by connecting to my
>hosting providers' "smart host" using authenticated SMTP.
>
>My home system's hostname is zbmc.eu but I don't use that domain in my
>E-Mail address, I use isbd.co.uk which domain is hosted at one of my
>hosting providers (mythic-beasts.com).
>
>However most of the time I use my hosting at gandi.net to send my
>E-Mail, so mail from ch...@isbd.co.uk originates on zbmc.eu, is
>transferred by authenticated SMTP to mail.gandi.net and is sent on
>from there to whatever its destination is.
>As I understand it the SPF records for mail.gandi.net purely confirm
>to a receiving mail server that the mail is coming from mail.gandi.net
>and reverse DNS look-up confirms that it really is mail.gandi.net.
>Have I got that right?
On Sat, Jan 14, 2023 at 04:55:45PM +0100, Matus UHLAR - fantomas wrote:
SPF records for mail.gandi.net are checked when someone sends mail from
@mail.gandi.net (you don't) or when server introduces itself as
mail.gandi.net (I assume yours introduces as zbmc.eu).
On 14.01.23 16:45, Chris Green wrote:
Yes, my server's postfix is on zbmc.eu but since the connection to
Gandi is authenticated I assume Gandi will accept my E-Mails anyway.
usually yes, they of course can do that (but there's no point)
so, you should not care about SPF record for mail.gandi.net but for SPF
record for isbd.co.uk
How does isbd.co.uk's SPF record get involved, it's hosted at Mythic
Beasts so never sees my E-Mails sent from zbmc.eu to Gandi.
when you or someone send mail from @isbd.co.uk, the recipient server checks
SPF records of isbd.co.uk to see if the sending client is allowed to send
mail from that domain.
mail.gandi.net may not check SPF for that domain if you use their server
(they may), and when mail.gandi.net sends that mail to anyone, the
destination server will look if mail.gandi.net is listed in SPF record of
isbd.co.uk.
As above, I don't see how isbd.co.uk's SPF record gets involved at
all, isbd.co.uk is hosted at mythic-beasts.com. I have another
(unrelated) domain registered at Gandi (that I thus have a password
there that I use to autheticate the connection from zbmc.eu)
You send mail from @isbd.co.uk, the SPF is designed to stop people using
domains they have no relation to. So, if you use @isbd.co.uk in your sender
address, they will check if you are allowed to send mail from @isbd.co.uk.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
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