ftp://ftp.ietf.org/internet-drafts/draft-ietf-drums-smtpupd-09.txt
I'm not sure how many people on the list have read this draft, but it's
rather interesting. Basically, it aims to consolidate RFCs 821, 974,
1035, 1123 and the SMTP Extension RFCs into a single document. It's sort
of momentous in that when it becomes an RFC, it will make RFC821 obsolete
for the first time in 17 years.
I haven't noticed anything that needs to be changed in Exim to make it
comply with the specification, but there are a few places where
documentation could do with an update. For example:
4.5.3 Sizes and Timeouts
recipients buffer
The minimum total number of recipients that must be
buffered is 100 recipients. Rejection of messages (for excessive
recipients) with fewer than 100 RCPT TO commands is a violation of this
specification. The general principle that relaying SMTP servers MUST
NOT, and delivery SMTP servers SHOULD NOT, perform validation tests on
message headers suggests that rejecting a message based on the total
number of recipients shown in header fields is to be discouraged. A
server which imposes a limit on the number of recipients MUST behave in
an orderly fashion, such as to reject additional addresses over its limit
rather than silently discarding addresses previously accepted. A client
that needs to deliver a message containing over 100 RCPT TO commands
SHOULD be prepared to transmit in 100-recipient "chunks" if the server
declines to accept more than 100 recipients in a single message.
Exim allows any integer to be set for the "recipients_max" option (but
defaults to unlimited). Under the new spec, the documentation should note
that while any value is acceptable, values between 1 and 99 will make your
server non-compliant.
The draft would also allow a few older features to be removed from Exim
without losing compliance. A "minimum" implementation of an SMTP server
is no longer required to support the VRFY command. There are also a
number of changes to "default" actions that servers should take,
especially on the topic of source routing.
All in all, an interesting read for anyone who is familiar with the
protocols behind mail instead of just the administration of the server.
--
j.
James FitzGibbon james@???
System Engineer, ACC Global Net Voice/Fax (416)207-7171/7610
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