Re: [mailop] Maximum message size

[Hans-Martin Mosner via mailop]

Am 24.10.20 um 19:19 schrieb John Levine via mailop:
>
> FTP was swell forty years ago but it's obsolete now. Nothing,
> including the user names or passwords, is encrypted, and it needs to
> set up a second TCP connection for each data transfer which confuses
> NATs and firewalls.
>
> There are better alternatives now, of course. scp and sftp which run
> over ssh seem to be the ones of choice although they don't have the
> anonymous option that FTP does.
>
>> automatically and transparently to the user, given only recipient's email
>> address - that's the way "sendfile" worked.
> Wow, what a spammer's dream, drop my malware right into the victim's folder.
>
scp and sftp are also relatively cumbersome. Services like dropbox etc. are 
acceptable form a UX perspective (in my
opinion) as they work through the omnipresent browser interface, but their 
privacy is pretty weak.

However, it's really easy for an organization to set up a server with ownCloud 
or Nextcloud to enable their users to
store files and send download links in their mails. Browser access using TLS 
ensures both transport privacy as well as
the ability to verify that a file is being provided by the organization of the 
mail sender.

The private cloud options enable both anonymous download (by publicly providing 
links to a file or directory) as well as
anonymous upload (by providing links to a directory into which can files be 
dropped).

I know that many companies are not willing or able to set up their own 
co-located or rented server, and in such cases
using public cloud storage services with encrypted files may be an option. 
However, this requires more cooperation by
the users to ensure confidentiality of documents.

Cheers,
Hans-Martin


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Re: [mailop] Maximum message size

[John Levine via mailop]

In article <20201024112039.ga5...@rafa.eu.org>,
Jaroslaw Rafa via mailop  wrote:
>Dnia 24.10.2020 o godz. 01:36:08 Kenneth Porter via mailop pisze:
>> 
>> The biggest problem with getting business partners to use FTP is
>> that they're often not allowed to use 3rd party software (like
>
>In my opinion, the biggest problem to use FTP is that it requires several
>steps which are not quite intuitive for inexperienced user.

FTP was swell forty years ago but it's obsolete now. Nothing,
including the user names or passwords, is encrypted, and it needs to
set up a second TCP connection for each data transfer which confuses
NATs and firewalls.

There are better alternatives now, of course. scp and sftp which run
over ssh seem to be the ones of choice although they don't have the
anonymous option that FTP does.

>automatically and transparently to the user, given only recipient's email
>address - that's the way "sendfile" worked.

Wow, what a spammer's dream, drop my malware right into the victim's folder.

-- 
Regards,
John Levine, jo...@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

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Re: [mailop] Maximum message size

[Andrew C Aitchison via mailop]

On Sat, 24 Oct 2020, Sidsel Jensen via mailop wrote:


On 23 Oct 2020, at 20.08, Michael Peddemors via mailop  
wrote:

By default we still distribute with a 10MG maximum size, but frankly almost all 
of our customers has bumped it to the maximum we recommend, which is 20MG.  
(the odd one even went to 30, but we don't recommend that)

Too bad this isnt' escalated to a recommended standard.

How about we use this as a chance to discuss this with other groups such as 
M3AAWG and IETF, to try to come up with a written consensus for others to 
follow.. (I think gmail still has the 25MG max size, but someone can correct me 
on that)



Hi Michael

Looks like nobody answered you on that point regarding discussion of and 
finding some sort of consensus on the size limits on mails.
I for one, think it sounds like a good idea for a discussion point in M3AAWG 
and/or IETF. *thumbs up*

The result for us, is that we have fx. specific error msgs for customers adding 
attachments which are above the limits for fx. what Hotmail and Microsoft 
accepts.

Result: "550 5.7.1 Message size 95566050b too big for delivery to hotmail.com 
(31457280b max)" (in 00:00:00.005)
Result: "550 5.7.1 Message size 32635093b too big for delivery to live.nl (31457280b 
max)" (in 00:00:00.002)
Result: "550 5.7.1 Message size 41809588b too big for delivery to live.se (31457280b 
max)" (in 00:00:00.002)

- right now it’s a manual task to maintain and review these once in a while.
(Aka a pet - not cattle…) Sounds like others have a similar problem.


How reliable is the SIZE value in the EHLO response ?

--
Andrew C. Aitchison Kendal, UK
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Re: [mailop] Maximum message size

[Suresh Ramasubramanian via mailop]

“be conservative in what yoyu send and generous in what you accept” has its 
uses when you separate your inbound and outbound mtas. Discuss.

From: mailop  on behalf of Sidsel Jensen via mailop 

Reply to: Sidsel Jensen 
Date: Saturday, 24 October 2020 at 5:50 PM
To: mailop 
Subject: Re: [mailop] Maximum message size

On 23 Oct 2020, at 20.08, Michael Peddemors via mailop 
mailto:mailop@mailop.org>> wrote:

By default we still distribute with a 10MG maximum size, but frankly almost all 
of our customers has bumped it to the maximum we recommend, which is 20MG.  
(the odd one even went to 30, but we don't recommend that)

Too bad this isnt' escalated to a recommended standard.

How about we use this as a chance to discuss this with other groups such as 
M3AAWG and IETF, to try to come up with a written consensus for others to 
follow.. (I think gmail still has the 25MG max size, but someone can correct me 
on that)

Hi Michael

Looks like nobody answered you on that point regarding discussion of and 
finding some sort of consensus on the size limits on mails.
I for one, think it sounds like a good idea for a discussion point in M3AAWG 
and/or IETF. *thumbs up*

The result for us, is that we have fx. specific error msgs for customers adding 
attachments which are above the limits for fx. what Hotmail and Microsoft 
accepts.

Result: "550 5.7.1 Message size 95566050b too big for delivery to 
hotmail.com (31457280b max)" (in 00:00:00.005)
Result: "550 5.7.1 Message size 32635093b too big for delivery to 
live.nl (31457280b max)" (in 00:00:00.002)
Result: "550 5.7.1 Message size 41809588b too big for delivery to 
live.se (31457280b max)" (in 00:00:00.002)

- right now it’s a manual task to maintain and review these once in a while.
(Aka a pet - not cattle…) Sounds like others have a similar problem.

I believe our limit right now is 100MB.

Kind Regards,
Sidsel Jensen
Team manager Mail & Abuse, Systems Engineer @ One.com


On 2020-10-23 10:48 a.m., Evert Mouw via mailop wrote:

On 10/23/20 7:23 PM, Adam Moffett via mailop wrote:

I'm at 200MB maximum message size and have someone requesting we increase that 
limit.

Is there any current consensus on what it should be?
Current default max. message size for Postfix configurations:
message_size_limit (default: 1024) / The maximal size in bytes of a 
message, including envelope information.
http://www.postfix.org/postconf.5.html
Also Microsoft Exchange 2019 has a default limit of 10 MB.
https://docs.microsoft.com/en-us/exchange/mail-flow/message-size-limits?view=exchserver-2019
Increase the limit all you want but don't expect other parties to accept or 
deliver large messages. I would not increase, but DEcrease the limit in your 
case. Learn the user to use other file transfer methods, or if you like 
Thunderbird, check this:
https://support.mozilla.org/en-US/kb/filelink-large-attachments
Regards, Evert
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Re: [mailop] Maximum message size

[Sidsel Jensen via mailop]

> On 23 Oct 2020, at 20.08, Michael Peddemors via mailop  
> wrote:
> 
> By default we still distribute with a 10MG maximum size, but frankly almost 
> all of our customers has bumped it to the maximum we recommend, which is 
> 20MG.  (the odd one even went to 30, but we don't recommend that)
> 
> Too bad this isnt' escalated to a recommended standard.
> 
> How about we use this as a chance to discuss this with other groups such as 
> M3AAWG and IETF, to try to come up with a written consensus for others to 
> follow.. (I think gmail still has the 25MG max size, but someone can correct 
> me on that)
> 

Hi Michael

Looks like nobody answered you on that point regarding discussion of and 
finding some sort of consensus on the size limits on mails.
I for one, think it sounds like a good idea for a discussion point in M3AAWG 
and/or IETF. *thumbs up*

The result for us, is that we have fx. specific error msgs for customers adding 
attachments which are above the limits for fx. what Hotmail and Microsoft 
accepts.

Result: "550 5.7.1 Message size 95566050b too big for delivery to hotmail.com 
(31457280b max)" (in 00:00:00.005)
Result: "550 5.7.1 Message size 32635093b too big for delivery to live.nl 
(31457280b max)" (in 00:00:00.002)
Result: "550 5.7.1 Message size 41809588b too big for delivery to live.se 
(31457280b max)" (in 00:00:00.002)

- right now it’s a manual task to maintain and review these once in a while.
(Aka a pet - not cattle…) Sounds like others have a similar problem.

I believe our limit right now is 100MB.

Kind Regards,
Sidsel Jensen
Team manager Mail & Abuse, Systems Engineer @ One.com 
> On 2020-10-23 10:48 a.m., Evert Mouw via mailop wrote:
>> On 10/23/20 7:23 PM, Adam Moffett via mailop wrote:
>>> I'm at 200MB maximum message size and have someone requesting we increase 
>>> that limit.
>>> 
>>> Is there any current consensus on what it should be?
>>> 
>> Current default max. message size for Postfix configurations:
>> message_size_limit (default: 1024) / The maximal size in bytes of a 
>> message, including envelope information.
>> http://www.postfix.org/postconf.5.html
>> Also Microsoft Exchange 2019 has a default limit of 10 MB.
>> https://docs.microsoft.com/en-us/exchange/mail-flow/message-size-limits?view=exchserver-2019
>> Increase the limit all you want but don't expect other parties to accept or 
>> deliver large messages. I would not increase, but DEcrease the limit in your 
>> case. Learn the user to use other file transfer methods, or if you like 
>> Thunderbird, check this:
>> https://support.mozilla.org/en-US/kb/filelink-large-attachments
>> Regards, Evert
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Re: [mailop] Maximum message size

[Jaroslaw Rafa via mailop]

Dnia 24.10.2020 o godz. 01:36:08 Kenneth Porter via mailop pisze:
> 
> The biggest problem with getting business partners to use FTP is
> that they're often not allowed to use 3rd party software (like

In my opinion, the biggest problem to use FTP is that it requires several
steps which are not quite intuitive for inexperienced user. You have first
to use FTP to put file on the server, then send the info about file's
location to the recipient and the recipient has again to use FTP to get the
file from server. I am thinking about something that does these operations
automatically and transparently to the user, given only recipient's email
address - that's the way "sendfile" worked.
-- 
Regards,
   Jaroslaw Rafa
   r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."
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Re: [mailop] Maximum message size

[Kenneth Porter via mailop]

--On Saturday, October 24, 2020 2:35 AM +0200 Jaroslaw Rafa via mailop 
 wrote:



Why nobody ever tried to write a RFC for something like
"sendfile" and implement it in MUAs?


There was discussion recently on the Internet History list about FTP and 
how  it used to be how email was done before the rise of other email 
protocols. You composed a message and dropped it in the other user's mail 
directory. Headers came later as the routing system got more complicated.


See the thread "FTP RIP" here:



The biggest problem with getting business partners to use FTP is that 
they're often not allowed to use 3rd party software (like FileZilla) and 
the stock Microsoft command line FTP client is pretty lame and can't do 
secure transfers. I tried using DAV for awhile, but the MS DAV client 
didn't work well with the DAV server module in Apache.


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Re: [mailop] Maximum message size - tag along question.

[Mark Foster via mailop]

My usual limit is 100MB and then I explain to my users that:

1) That's the _email size limit_ and not the size limit for an attachment to an 
email
2) Email is inefficient when used for transferring files, thus overhead
3) Email is not intended to be a system for routinely moving large files
4) You can't garuntee what other mail servers in the chain may have enabled as 
maximum size limits, so upping the local limit isn't going to solve all your 
problems
5) Look at OneDrive, Dropbox or Google Drive as readily available ad-hoc file 
transfer options.

At 100MB I hear very few complaints. I certainly wouldn't be making the limit 
any higher for the OP's scenario.

Some legacy mail systems I have to deal with, struggle with the combination of 
large email + large number of recipients (when processing rules require you to 
bifurcate the email into one-email-per-recipient in order to enable 
per-recipient rule handling, your single 100MB email can become several 
gigabytes of processing) so that's another potential factor.

Mark.

-Original Message-
From: mailop  On Behalf Of Grant Taylor via mailop
Sent: Saturday, 24 October 2020 6:37 pm
To: mailop@mailop.org
Subject: [mailop] Maximum message size - tag along question.

Do you take into account the 4/3 inflation with Base64 encoding and / or allow 
for any message body when setting the maximum message size that your servers 
allow?



--
Grant. . . .
unix || die


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