Wietse Venema via Postfix-users wrote in
<4wk8qr69xlzj...@spike.porcupine.org>:
|Steffen Nurpmeso via Postfix-users:
|> That looks doable, but it seems to me that i then have to use
|> a very high limit which postfix announces via "250-SIZE", and
|> reject many (practically all) emails because of size restrictions
|
|You can suppress the SIZE announcement with
|
| smtpd_discard_ehlo_keywords = size, silent_discard
Ah, good to know there is a way to do that. And with
smtpd_discard_ehlo_keyword_address_maps i can selectively do so,
which could be my way to go. (And thankfully there is the
# smtpd_discard_ehlo_keyword_address_maps = cidr:/path/to/file
# /path/to/file:
# 10.0.0.0/24 chunking, silent-discard
in the very detailed smtpd_forbid_bare_newline documentation.)
To my pity this only allows CIDR not hostnames, and *that* could
become *my* use case for SPF, as Google documents how to figure
out its IP addresses (dig _spf.google.com TXT, plus digging the
same for the given include: directive, currently "v=spf1
include:_netblocks.google.com include:_netblocks2.google.com
include:_netblocks3.google.com ~all"). Ok, SPF is useful.
|but you'd still have to configure message_size_limit as the maximal
|upperbound of the allowed message sizes.
I surely want this.
..in this context i reread RFC 9422 "The LIMITS SMTP Service
Extension" from this year and saw the enormous
S: 250-SIZE 100000000
and
All that said, decades of operational experience with the SMTP "SIZE"
extension [SIZE], which provides servers with the ability to indicate
message size, indicates that such abuse is rare and unlikely to be a
significant problem.
as well as RFC 3463 "Enhanced Mail System Status Codes", and since
5.XXX.XXX Permanent Failure
A permanent failure is one which is not likely to be resolved
by resending the message in the current form. Some change to
the message or the destination must be made for successful
delivery.
is "so generic" that i think the approach of not offering SIZE and
then failing with a 5. is my way. (But .. how about allowing
negative message_size_limit to mean "announce SIZE, but without
a value", so that clients (who understand that, mine does not
(yet)) get an immediate notion that 5. could mean size limit,
instead of only assuming that 5. can mean a size limit, you know.)
Thank you,
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
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