1) the incentive is to make sure their messages delivered.
2) increasingly, antispam filters are taking out legitimate
communications from
businesses. The use of a stamp would allow them to bypass
the filters without
requiring the recipient to do anything special (i.e. white
list, filter exception).
[I don't see the distinction between these arguments]
The same argument holds for authentication based approaches that
do not involve a per message charge.
If C|Net has a certificate that proves that they sent an outgoing
message their subscribers know it came from them and is not spam.
This mail has an S/MIME signature, you can tell it came from me.
Phill
smime.p7s
Description: S/MIME cryptographic signature