would pacbell filtering all multicast at all CPE equipemt fall into your
bucket, where do you draw the line?
At IP, as Bob Braden said.
SMTP is _over_ IP.
Wrong. RFC821 says:
SMTP is independent of the particular transmission subsystem and
requires only a reliable ordered data stream channel. Appendices A,
B, C, and D describe the use of SMTP with various transport services.
A Glossary provides the definitions of terms as used in this
Multicast _redefines_ IP (or portions of the address space thereof); it
could be argued that a service provider sells 'Internet' without selling
See STD1 for a list of "required" protocols.