I'd like to draw a parallel between "outgoing messages" and "outgoing IP
Here, I'm using the term "outgoing" in a very broad sense.
To reduce the amount of IP packet spoofing, router software manufacturers and
network admins have been encouraged to check "outgoing" packets and filter
packets containing "spoofed" addresses. This can be easily done in routers
could/should/has (?) reduced or eliminated spoofed packets traversing the
Wouldn't it be nice if the same sort of thing could be done with email
no, it wouldn't be nice to be forced to always submit mail from the same
IP addresses are inherently tied to network locations. email addresses are not.
Imagine all the viruses that would be blocked because they could only send
behalf of the "originating location's mail domain".
the viruses wouldn't be blocked, they'd just have different From addresses.