On 9/13/23 6:04 AM, Jaroslaw Rafa via mailop wrote:
If someone forwards mail to his/her account, they obviously know
*from where* they forward mail.
Aside: I originally thought you were referring to which senders would
be sending messages that would get forwarded. But after reading you
next statement, I realized that you were referring to the (intermediate)
system(s) doing the forwarding.
So allow your user to specify a list of IP addresses of servers
from where the mail is forwarded.
I don't buy it.
Even if people did know the IP address of their (former) forwarding
inbox provider server(s) at one point in time, things change. Often
this change is unbeknownst to the end users. Maybe it's simply a change
within the providers network. Maybe the provider outsourced to a 3rd
party. Maybe the provider insourced from a 3rd party. Maintaining this
list is going to be untenable for most end users.
Email from these servers to that particular user will be exempt from
SPF/DKIM/DMARC checks.
I see that as more complicated than likely desired and potential to be
abused. Especially with the complication of multiple recipients per
message, one of whom might have more such allow listing.
(If the user doesn't know the IP address from which the mail is sent,
he/she can probably easily find someone who knows, at the site from
where the forward originates.)
That's an example of trouble / needing help to do what you suggest from
the word go.
--
Grant. . . .
unix || die
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