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Storage Limits
What is a Storage Limit?
Old fashioned email systems didn't have
to deal with this issue like we do now. Traditional
email systems only store email until the client
connects; then email is downloaded to the client's
machine and deleted from the server.
Exchange turns this on its head, and
stores everything on the server. The advantages are
huge. But it does create the issue of storage limits.
The storage limit defines how much content a user is
allowed to store on the server.
Every mailbox on Webville's Exchange
servers has a storage limit. Here's how it works.
The server constantly monitors the
amount of content in your mailbox in Megabytes (MB). It
takes action automatically to enforce the limits
established for that mailbox by the
administrator.
I want a bigger mailbox!
We're happy to increase the limits on
your mailbox. There are many advantages to storing your
important email, attachments and other documents on the
Exchange server. Just let us know what size mailbox you
want. See the Exchange Hosting
Pricing page for costs.
Three Limits?
Although we talk about one limit,
calling our standard mailbox a 100 MB mailbox, there are
actually three limits on each mailbox and three types of
action the server can take. The first is a warning
message. Each night, the server runs a process to
automatically generate warning messages. You will
receive a warning message if the amount of content in
your mailbox exceeds 90% of the set limit.
For example, if your storage limit is
100 MB, you will receive a warning message when your
actual storage utilization exceeds 90 MB. Since the
warning messages are generated automatically every
night, you will receive the message every day that your
storage utilization continues to exceed 90% of your
limit.
The second type of limit is called
"prohibit send." This is the limit we commonly refer to.
If you exceed your storage limit, the server will not
allow you to send additional email. When you try to send
an email, it will be returned to you with a message
explaining that you have exceeded your storage
limit.
The third type of limit is "prohibit
send and receive." If the content of your mailbox
exceeds 200% of your storage limit, the server will also
refuse to accept additional incoming email for that
mailbox. Incoming email will be returned to the sender
with an error message.
Here is a screen shot of the interface
in the Exchange server administration tool, illustrating
the storage limit settings.
Please note, the administrator's only
role in all of this is to set the limits. The server
automatically takes the actions described based on these
settings and generates the particular messages you
see.
I keep getting this error...
Although warning messages are generated
only once a day, the server constantly monitors the send
and receive limits, and will allow or disallow the
sending and receiving of email at any time.
For example, if you receive a large file
attachment that puts you over your limit, you may get an
unpleasant surprise when you try to reply to it. But if
you save that attachment to your computer's hard disk,
and delete it from your mailbox, you may get back under
your limit and continue normally.
How big is my mailbox now?
Here's how to check the current size of
your mailbox:
- Start Outlook
- Right-click the Outlook Today icon,
choose Properties from the context menu, and click the
Folder Size button.
Usually when people go over their
storage limit, it's because of large file attachments.
Fortunately, there are some good ways to watch for
these, hunt them down, and target them for
termination.
Outlook provides several columns in the
standard view of your inbox, including From, Subject,
Received (date and time), etc. By default, it does not
include a column showing the size of the item, but you
can easily add a column to show the size. Here's
how.
- On the View menu, point to Current
View, and then click Customize Current View.
- Click Fields.
- Click Size in the list of
available fields box.
- Click Add, then click OK.
Now that you have a size column, sort
the inbox by size to find the biggest offenders. To sort
the inbox by any particular column, click that column
header. Click repeatedly to toggle between ascending and
descending sort order.
At this point your inbox is sorted by
size of item, in descending order. It should be easy to
figure out which items are using up your storage
allocation.
After you finish your inbox, look at
your Sent Items and Deleted Items folders. Those are
usually where you find the culprits.
Why is all this necessary?
The obvious reason is that storage
hardware costs money, especially server-quality,
redundant storage, which has to be backed up to tape
regularly. But there are other reasons you may not be
aware of.
The receive limit in particular is very
important to protecting the Exchange server. Without a
receive limit, any particular mailbox could receive so
much mail in such a short time that it could bring the
server to a stop.
This did not happen at Webville, but we
were called in to consult with a company, when a poorly
configured forwarding rule caused two servers to get
into a loop, sending a message back and forth until one
of the servers stopped because its disk was
full.
Similarly, a classic denial of service
(DOS) attack is to send a huge amount of email to a
particular address, intending to cripple the server
which hosts that address, as well as the user of the
address.
The storage limits protect all
Webville's Exchange Hosting customers from these type of
problems, and help ensure the robustness, high
performance and dependability of our
services. | 
