Bruce Lilly wrote:
o aliasing and list expansion can only take place where the
local-part of the (SMTP envelope) path is interpreted;
architecturally that is at an MDA
Of course, and that's the fundamental problem in 1123 and with
so called "forwarders".
A description of the mail system architecture is incomplete
unless it discusses the gateway vs. message fragment
reassembly issues documented in RFC 1344, ignorance of which
has led to security problems.
We all have our pet peeves, and yours is message/partial. IMHO
such MIME issues are out of scope for an RfC about "mail-arch",
it's too special.