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Effects of very large message_size_limit?

Hi, I'm wondering what the downside of setting a large
message_size_limit are?

By "large" I mean 30MB, 40MB, 50MB

I think sendmail has a default of no restriction for message size - that
seems crazy, but maybe I don't understand the risks well enough.

Comments

Re: Effects of very large message_size_limit?

By Benny Pedersen at 09/15/2016 - 12:17

On 2016-09-15 07:19, <a href="mailto: ... at insiberia dot net"> ... at insiberia dot net</a> wrote:
accept and bounce imho

use multipart mime instead, or cloud storages for fileshareing

thunderbird can do this with a plugin

dont know if others can make it simple

Re: Effects of very large message_size_limit?

By Robert Schetterer at 09/15/2016 - 02:34

Am 15.09.2016 um 07:19 schrieb ... at insiberia dot net:
some freemailers have a limit of 10 MB, so its perhaps a good choice to
set it for outgoing external mail, for inside a higher amount up to 50
sometimes makes sense

Best Regards
MfG Robert Schetterer

Re: Effects of very large message_size_limit?

By mrobti at 09/15/2016 - 16:00

On 2016-09-14 23:34, Robert Schetterer wrote:
I'm aware of the range of limits, for example:

<a href="https://www.outlook-apps.com/maximum-email-size/" title="https://www.outlook-apps.com/maximum-email-size/">https://www.outlook-apps.com/maximum-email-size/</a>

But can anyone answer my question - what factors should I consider when
increasing the limit in the 30-50MB range (or higher)? Are there
drawbacks to doing this?

Re: Effects of very large message_size_limit?

By LuKreme at 09/16/2016 - 09:27

On Thu Sep 15 2016 14:00:46 <a href="mailto: ... at insiberia dot net"> ... at insiberia dot net</a> < ... at insiberia dot net> said:
The main factor is that the limit used by most everyone is about 20-25MB so if you accept larger attachments, you will often not be able to send those mails on for delivery or forward or whatever. I set my limit (increased it) to 25MB to match gmail and that gives me a perfect reason if anyone asks (If the limit is larger, then people who forward their mail to or from gmail will have problems).

As far as other drawbacks, if you are still using mbox files your files will get very large very fast, and that’s incredibly inefficient with mbox. Nothing quite like trying to fix a 12GB mbox file.

There is absolutely no need to send large files via email as there are hundreds, if no thousands of other options, almost all of which will be more robust, more secure, and have a much smaller impact on what is still a critical service for most people.

Re: Effects of very large message_size_limit?

By Wietse Venema at 09/15/2016 - 16:55

Obviously, the size of the file system determines how large your
email messages can be. Postfix will stop accepting mail delivery
transactions when the free space in the queue directory is less
than 1.5 times the message size limit.

Wietse

Re: Effects of very large message_size_limit?

By mrobti at 09/15/2016 - 17:12

On 2016-09-15 13:55, <a href="mailto: ... at porcupine dot org"> ... at porcupine dot org</a> wrote:
I see, so Postfix doesn't experience any bottlenecks or congestion in
other ways with 50MB+ attachments? If size of filesystem is the main
concern, quotas are easy way to keep it under control. In that case, is
there argument against a limit of say 100MB?

Re: Effects of very large message_size_limit?

By Wietse Venema at 09/15/2016 - 17:33

The answer depends on how fast your network is, how fast your file
system is, whether recently accessed files can be cached in main
memory, and what kinds of deep content inspection you're doing. A
matchbox-size firewall appliance will struggle with email messages
that a beefier box will handle without a sweat.

Wietse