Re: [Imap-protocol] Working around the evils of LITERAL+

On Wed, Mar 27, 2013, at 10:03 AM, Brandon Long wrote:




On Tue, Mar 26, 2013 at 2:52 PM, Timo Sirainen <[1][email protected]> wrote:

On 26.3.2013, at 23.26, Brandon Long <[2][email protected]> wrote:



> This was because of some unfortunate combination of factors.  For
one, we have a maximum message size on our server, with no real way to
make that available to IMAP (maybe via GETQUOTA, but if no clients
check it, that's not that useful).  For two, we have an inbound
bandwidth quota to protect against both broken clients and attempts to
use Gmail IMAP as a storage system.

>

> So, if a user attempted to draft a message larger than our limit
(35MB),



Seems a bit small limit to me.


Heh, sure, we get that from some users from time to time, but almost
every part of our system requires loading the whole message into memory
at some point (or two copies), and that adds up quick.  And its fairly
typical from the major webmail providers.  And frankly, SMTP is a
pretty poor file transfer protocol, what with the base64 encoding and
the lack of checksumming or restartability and the duplicate delivery
vagueness.



We very carefully DON'T ever load the entire message into memory at
once.  It gets streamed to a temporary file and mmaped, but not
actually loaded into memory - allowing the OS to decide how much to
keep around as we parse through it.



As for your (later) question about what other sites do?  At FastMail we
allow users to store any size message so long as it's within their
quota.  We know (indeed, there are tools for usenet from way back) that
rar files or zip files can be split up into separate parts and stored
in separate messages if someone is going to be abusive.



SMTP sucks for sending big messages, but it doesn't stop people wanting
to do just that - for all the usual reasons that email is better than
$INSERT_OTHER_SERVICE_HERE.



(my short list is: own copy, persistent, immutable - hmm, I should
stick it in blog format.  Here:
[3]http://whatwouldazen.wordpress.com/2013/03/28/email-is-still-relevan
t/ - of course, it's soundbyte sized, but I think it hits the important
points)



Bron.



--
Bron Gondwana
[email protected]

References

1. mailto:[email protected]
2. mailto:[email protected]
3. http://whatwouldazen.wordpress.com/2013/03/28/email-is-still-relevant/

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