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Re: limit on attachment in mail to list

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  Re: limit on attachment in mail to list Byung-Hee HWANG <soyeomul@doraji.xyz> - 2023-11-09 14:50 +0100
    Re: limit on attachment in mail to list Greg Wooledge <greg@wooledge.org> - 2023-11-09 17:50 +0100
      Re: limit on attachment in mail to list <tomas@tuxteam.de> - 2023-11-10 06:50 +0100
        Re: limit on attachment in mail to list Greg Wooledge <greg@wooledge.org> - 2023-11-10 13:50 +0100
    Re: limit on attachment in mail to list Gareth Evans <donotspam@fastmail.fm> - 2023-11-11 21:20 +0100
      Re: limit on attachment in mail to list Greg Wooledge <greg@wooledge.org> - 2023-11-11 21:30 +0100
        Re: limit on attachment in mail to list "Thomas Schmitt" <scdbackup@gmx.net> - 2023-11-11 22:00 +0100
          Re: limit on attachment in mail to list "Gareth Evans" <donotspam@fastmail.fm> - 2023-11-12 14:40 +0100

#263282 — Re: limit on attachment in mail to list

On Thu, Nov 09, 2023 at 02:04:39AM -0500, hlyg wrote:
> list doesn't seem to accept my mail, because of big attachment i believe
> 
> what is max size of attachment allowed in list? Thanks!
> 

Hellow, 

This is my guess:

<quote>
220 bendel.debian.org ESMTP Postfix
ehlo penguin
250-bendel.debian.org
250-PIPELINING
250-SIZE 30720000
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 CHUNKING
quit
221 2.0.0 Bye
</quote>

So 30720000 bytes?

Still it was not tested myself...


Sincerely, Byung-Hee

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#263293

On Thu, Nov 09, 2023 at 01:47:01PM +0000, Byung-Hee HWANG wrote:
> On Thu, Nov 09, 2023 at 02:04:39AM -0500, hlyg wrote:
> > list doesn't seem to accept my mail, because of big attachment i believe
> > 
> > what is max size of attachment allowed in list? Thanks!

> This is my guess:
> 
> <quote>
> 220 bendel.debian.org ESMTP Postfix
> ehlo penguin
> 250-bendel.debian.org
> 250-PIPELINING
> 250-SIZE 30720000
> 250-STARTTLS
> 250-ENHANCEDSTATUSCODES
> 250-8BITMIME
> 250 CHUNKING
> quit
> 221 2.0.0 Bye
> </quote>
> 
> So 30720000 bytes?

That looks like an upper limit on the total message size, not the size
of a MIME attachment inside the message.

Restrictions on the message content (such as attachment size limits)
would have to be enforced by something that parses the message body.
SMTP receivers usually don't do that (although they may hand the message
off to an anti-virus scanner or something which does).

The OP claimed they never received a bounce, so presumably their message
was simply dropped into the bit bucket when it failed whatever criteria
were applied.  This is sensible behavior in any kind of post-SMTP
processing, although it's super frustrating for a legitimate sender who
now has no idea why their mail disappeared.

So, only the list admins would know the answer.

As a general policy, I would *never* attach an image to any email sent
to this list, regardless of size.  This list should remain text only.
If you absolutely have to send an image (photo of a misbehaving X server
or whatever), your best bet would be to host the image on your personal
web server or possibly on some global image-sharing web site (although
very few of these are suitable), and include a URL to it in your email.

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#263323

[Multipart message — attachments visible in raw view] — view raw

On Thu, Nov 09, 2023 at 11:40:17AM -0500, Greg Wooledge wrote:
> On Thu, Nov 09, 2023 at 01:47:01PM +0000, Byung-Hee HWANG wrote:
> > On Thu, Nov 09, 2023 at 02:04:39AM -0500, hlyg wrote:
> > > list doesn't seem to accept my mail, because of big attachment i believe
> > > 
> > > what is max size of attachment allowed in list? Thanks!
> 
> > This is my guess:
> > 
> > <quote>
> > 220 bendel.debian.org ESMTP Postfix
> > ehlo penguin
> > 250-bendel.debian.org
> > 250-PIPELINING
> > 250-SIZE 30720000
> > 250-STARTTLS
> > 250-ENHANCEDSTATUSCODES
> > 250-8BITMIME
> > 250 CHUNKING
> > quit
> > 221 2.0.0 Bye
> > </quote>
> > 
> > So 30720000 bytes?
> 
> That looks like an upper limit on the total message size, not the size
> of a MIME attachment inside the message.

In another message, hlyg said the attachment is 1.2M, so with encoding
and things that's not very unplausible.

My take as far as now is that the message was rejected while the
protocol was "in flight" as above, and outlook.com didn't care to
generate an error message. Or you have to opt-in to an extra service
with them to be able to see them. Or something more preposterous
(Microsoft always tops my dirtiest fantasies).

> Restrictions on the message content (such as attachment size limits)
> would have to be enforced by something that parses the message body.
> SMTP receivers usually don't do that (although they may hand the message
> off to an anti-virus scanner or something which does).

This is standard nowadays. In the bad old days you did that after the
fact and had to generate a bounce message. Since the sender has control
over the address to bounce to, spammers have misused that to use MTAs
as bouncers for their stuff (mail backscatter [1]). So parsing the
message during reception ("connection-stage rejection", see also [1])
has become standard since the early 2000s, latest 2010 AFAIR.

> The OP claimed they never received a bounce, so presumably their message
> was simply dropped into the bit bucket when it failed whatever criteria
> were applied.  This is sensible behavior in any kind of post-SMTP
> processing, although it's super frustrating for a legitimate sender who
> now has no idea why their mail disappeared.

Actually, no. This is behaving in non-standard ways, and, as you see
above, it is avoidable.

> So, only the list admins would know the answer.

But whose list admins. My suspicion lies with the Outlook ones
(either they don't signal the rejection, or they eat the bounce,
or they had an Azure dropout or whatever). They are known to
behave erratically already.

Cheers

[1] https://en.wikipedia.org/wiki/Backscatter_(email)
-- 
t

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#263332

On Fri, Nov 10, 2023 at 06:40:45AM +0100, tomas@tuxteam.de wrote:
> But whose list admins. My suspicion lies with the Outlook ones
> (either they don't signal the rejection, or they eat the bounce,
> or they had an Azure dropout or whatever). They are known to
> behave erratically already.

I see a few choices here.

1) Someone ELSE can try to send a 1.2 MB image attachment to this
   mailing list, PRAY TO $DEITY THAT IT FAILS, and then report to us
   in detail what happened.

2) Someone could ASK THE DEBIAN LIST ADMINS what the exact criteria are.

3) We could DROP THIS WHOLE FREAKING DISCUSSION.  Sending image attachments
   of any size to a large mailing list is BAD and SHOULD NOT HAVE BEEN
   DONE TO BEGIN WITH.

I, personally, do not want to be the asshole who sends a 1.2 MB image
to a mailing list, just in case it somehow gets through, just to test
something that doesn't need to be tested.

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#263377

> On 9 Nov 2023, at 13:47, Byung-Hee HWANG <soyeomul@doraji.xyz> wrote:
> 
> [...]

> <quote>
> 220 bendel.debian.org ESMTP Postfix
> ehlo penguin
> 250-bendel.debian.org
> 250-PIPELINING
> 250-SIZE 30720000
> 250-STARTTLS
> 250-ENHANCEDSTATUSCODES
> 250-8BITMIME
> 250 CHUNKING
> quit
> 221 2.0.0 Bye
> </quote>

Hi Byung-Hee,

How did you generate that, assuming it's a response to some command(s)?

Thanks,
Gareth

> 
> So 30720000 bytes?
> 
> Still it was not tested myself...
> 
> 
> Sincerely, Byung-Hee
> 

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#263378

On Sat, Nov 11, 2023 at 08:16:20PM +0000, Gareth Evans wrote:
> > On 9 Nov 2023, at 13:47, Byung-Hee HWANG <soyeomul@doraji.xyz> wrote:
> > <quote>
> > 220 bendel.debian.org ESMTP Postfix
> > ehlo penguin
> > 250-bendel.debian.org
> > 250-PIPELINING
> > 250-SIZE 30720000
> > 250-STARTTLS
> > 250-ENHANCEDSTATUSCODES
> > 250-8BITMIME
> > 250 CHUNKING
> > quit
> > 221 2.0.0 Bye
> > </quote>
> 
> Hi Byung-Hee,
> 
> How did you generate that, assuming it's a response to some command(s)?

Telnet to bendel, port 25.  Wait for the banner.  Type "EHLO your.domain".
Type "quit" to get out.

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#263381

Hi,

> On Sat, Nov 11, 2023 at 08:16:20PM +0000, Gareth Evans wrote:
> > > On 9 Nov 2023, at 13:47, Byung-Hee HWANG <soyeomul@doraji.xyz> wrote:
> > > <quote>
> > > 220 bendel.debian.org ESMTP Postfix
> > > ehlo penguin
> > > 250-bendel.debian.org
> > > 250-PIPELINING
> > > 250-SIZE 30720000
> > > 250-STARTTLS
> > > 250-ENHANCEDSTATUSCODES
> > > 250-8BITMIME
> > > 250 CHUNKING
> > > quit
> > > 221 2.0.0 Bye
> > > </quote>
> >
> > Hi Byung-Hee,
> >
> > How did you generate that, assuming it's a response to some command(s)?
>
> Telnet to bendel, port 25.  Wait for the banner.  Type "EHLO your.domain".
> Type "quit" to get out.

The protocol is named SMTP.
  https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol


Have a nice day :)

Thomas

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#263411

On Sat 11 Nov 2023, at 20:56, Thomas Schmitt <scdbackup@gmx.net> wrote:
On Sat 11 Nov 2023, at 20:23, Greg Wooledge <greg@wooledge.org> wrote:
>> Telnet to bendel, port 25.  Wait for the banner.  Type "EHLO your.domain".
>> Type "quit" to get out.
>
> The protocol is named SMTP.
>   https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol

Oh yes ;)  

Thanks to Greg and Thomas.

Gareth

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