[exim] Quota Limits - Setting Greater Amounts

Hello all,

Been using Exim for several years.

I have a setup that checks a file for the quote size and I then use a MySQL backend with virtual users.  Here is a snippet of what I currently have:

maildir_format
maildir_tag = ,S=message_size
maildir_use_size_file = true
maildir_quota_directory_regex = ^(?:cur|new|\..*)$
current_directory = /
quota = ${lookup mysql{SELECT quota FROM horde_users WHERE user_uid="${local_part}@${domain}"}{${value}999}}
quota_warn_threshold = 90%
quota_is_inclusive = false
quota_warn_message = "\
To: $local_part@$domain\n\
Subject: Mailbox Approaching Size Limit (90% Usage)\n\n\
Please note that your mailbox is approaching its limit.  Upon receiving this message, your mailbox was at 90% of capacity.\n"

However, please note that the "quota_warn_threshold" is set to an equal number as noted above.

Sometimes a user receives a very large e-mail that puts them over their quota limit.  Does anyone know of a way to set it so that if the value is at 90% or GREATER, the message is sent out?

In addition, once the individual has reached their quota limit, is there a way that a message saying "your mailbox is now closed" can be sent out?  I know that in an Exchange environment, that is possible.

I just have a few users that complain that they don't get the notice their mailbox is at 90% capacity and don't know that e-mails are bouncing because they have reached their limit.

Thank you!