Re: [exim] Quota Limits - Setting Greater Amounts

On Thu, May 17, 2012 at 6:40 PM, Todd Lyons <tlyons@???> wrote:
>> message never got generated because the state of the mailbox never was
>> in the range of 90-99%, where it would be detected and the warning
>> message generated.  I've not yet evaluated whether this is actually
>> the flow of the code, so take it with a grain of salt.
> It appears that this can in fact happen.  The fix seems like it would
> need to be one additional check along the lines of this pseudo-code:
>
> if ( quota_is_not_inclusive AND
>     current_size < quota_warning_size AND
>     current_size + incoming_msg_size > quota )
>
>  then do the warning message

After thinking about this, I don't think it's wise. First, I can't do
it without adding a bit of complexity. Second, the code currently
explicitly cancels the quota warning if quota limit is hit. Thinking
through it, here is what will happen if we did add this:
1. User has about 88% mailbox used.
2. Quota warning message is set at 90%.
3. A message attempts to be delivered that would put it over quota.
It's tempfailed and the remote queues it.
4. Exim generates a quota warning message into user's mailbox.
5. The remote attempts to redeliver a few minutes or an hour later, #3
and #4 happen again.
6. ...and again.

The user would log in to his mailbox the next day or after a weekend
of this and find 20+ quota warning messages that said his mailbox was
more than 90% (depends on your custom text exactly what it does say),
but when he looks at the size, it's actually still below that 90%
mark. It confuses the user, it will confuse any tech support who are
trying to help him, and it might even confuse the sysadmin. It
sounded like a nice idea at first, but the more I think about it, I
think it's doing exactly what it should in a very concise and
conceptually clear manner.

The only real fix for this is some combination of:
1. Set your quota warning lower, giving it more breathing room to
accept large messages.
2. Set your mail server to accept not quite as large messages so it
can't overrun that space between threshhold and max_quota.
3. Tell your users to use cloud storage for sharing files instead of SMTP.

...Todd
--
Always code as if the guy who ends up maintaining your code will be a
violent psychopath who knows where you live. -- Martin Golding