On Feb 28, 2021, at 01:32, Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:
Mark Sapiro writes:
On 2/27/21 4:36 AM, Stephen J. Turnbull wrote:
is legal, and I think that most servers will accept it, but RFC 5321 sets a limit of 64 octets on mailboxes[1], and your confirmation mailbox is 67 octets.
Since the -confirm+<token> part is fixed at 49 octets, this would imply a limit in list names of 15 octets. Ouch!
I'm pretty sure we would have run into this before, if there were a lot of servers out there imposing this limit. 15 octets is pretty darn short, there are probably quite a few list names out there longer than that. Not to mention that the RFC itself says "you SHOULD NOT be a jerk about this". :-) So I don't think this is a big problem in practice, and I hope Steve can reconfigure the obstructive server to not be so picky.
To be clear the 'obstructive server’ is mailman-core. :)
[ec2-user@ip-172-31-18-xxx ~]$ telnet 172.19.199.2 8024 Trying 172.19.199.2... Connected to 172.19.199.2. Escape character is '^]'. 220 mailman-core GNU Mailman LMTP runner 2.0 LHLO ip-172-31-18-xxx.us-west-2.compute.internal 250-mailman-core 250-SIZE 33554432 250-8BITMIME 250 HELP MAIL FROM:<stephen.s.w.matsmats@gmail.com> 250 OK RCPT TO:<matsmats-mm3-test1-confirm+d6f77a2572ef55a8b2c4ca0d77de8493fbb55856@mm3.aca-aws.s.uw.edu> 553 5.1.3 Error: malformed address RCPT TO:<matsmats-mm3-test1-confirm+d6f77a2572ef55a8b2c4ca0d77de8493fbb55@mm3.aca-aws.s.uw.edu> 250 OK quit 221 Bye
Didn’t really dig but my guess would be the LMTP from aiosmtpd.lmtp is actually throwing the 553.
For a bit of context, of the 25,801 mailman2 lists we have here at University of Washington 5,211 have names longer than 15 characters (we don’t have any lists with multibyte characters in their names). Our longest list name is 33 characters. I didn’t dump every config to see the number of lists that subscribe_policy set to confirm or confirm and approve. But I expect it’s a small minority.
steve
For Mailman, I doubt we need a full SHA1 (?) for the purpose. We can truncate the thing, probably opportunistically (ie, so the whole confirmation mailbox fits in 64 octets, or we could even parse the bounce message and resend only if we run into a problem).
Steve
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