Mailbox Storage and Limits Many users are asking, why there are limits to the size of the mailbox and messages? There are a number of reasons for having these limitations, which include client performance and responsiveness, backup and recovery, uptime, maintenance, storage, bandwidth, and SLA agreements. It is important to us that we are able to anticipate the needs of our users to improve their overall experience in communicating with their associates and organizing their daily tasks.
Having large mailbox size limits can compromise security and our ability to meet our customer guarantees. Here are some of the vulnerabilities an Exchange Admin is faced with when allowing its users to have large mailboxes:
- Denial of Service Attacks - Without a message and mailbox size limit, a hacker (whether internal or external) can easily implement a denial of service attack by sending messages with large attachments, ultimately using all available resources on the Exchange servers, thereby causing system failure. Implementing message size limits (both internal and external) can reduce the likelihood of this risk.
- Capacity Planning - The lack of quota management effectively limits any type of future capacity planning (e.g. cannot predict future database growth). In particular, if you have an SLA that dictates a backup/restore window you may not be able to meet that goal, due to not being able to control the database size metric.
- Network Utilization - Since the users will have unlimited mailbox sizes, network utilization will increase between client and server if users utilize OSTs or cached mode Outlook clients.
- Single Instance Storage - Single Instance Storage ratios may continue to decrease if reactionary measures are used to combat the lack of quotas (e.g. continually moving mailboxes around the enterprise to head off low disk space, SLA attainment, etc).
- Cost Impact - Due to the growth that will likely ensue without a proper quota management implementation, organizations will find that the cost per mailbox will continue to increase over time. In addition, more than likely, additional costs will accrue due to poor management of the solution, in terms of not having proper SLA/OLAs, moving mailboxes to head off capacity disasters, and overloading servers from a performance and capacity standpoint (due to the aforementioned mailbox moves).
- Performance Impact - A lack of quota management will mean that eventually the storage subsystem will not be able to sustain the I/O throughput required. As you increase the mailbox sizes, the number of items will increase and for most users this will mean an increase in the number of items in the key folders (Inbox, Sent Items, Calendar, etc); as the number of items increase, the I/O throughput per mailbox will increase (http://support.microsoft.com/?id=905803). In addition, since the amount of data increases, users may deploy desktop search programs, and when running in online mode, these search programs utilize Exchange server resources (http://support.microsoft.com/?id=905184).
- Ross Smith www.msexchangeteam.com
The End User Experience
It will also affect your local storage. We recommend our users use their Exchange profiles in “Cached Exchange Mode.” When enabled, an offline copy of the mailbox is kept on the local machine called an OST file. This allows users to work offline. This file will always be somewhat larger then your actual mailbox size.
Here is what Microsoft has to say about large OST files:One factor that can contribute to reduced performance is a large OST file. If the user’s OST file grows too large (for example, larger than 1 GB), Outlook with Cached Exchange Mode performance degrades. To improve response time in Outlook, users should either reduce the size of their mailbox (for example, by archiving older files) or disable Cached Exchange Mode. To help prevent large OST files, you can set a limit on the mailbox size in Exchange Server. You might also choose to disable synchronizing shared non-mail folders or disable synchronizing users’ Public Folder Favorites if you previously enabled the option in your deployment of Cached Exchange Mode.
-Microsoft TechNet
Mailbox size isn’t the only inhibiting factor to consider. The number of items a mailbox has in any given folder can also inhibit the performance of an exchange system, mainly for the end user. Operations will take longer such as, opening, saving, etc. Outlook plug-ins working with these folders in the background can effect the overall responsiveness of the client. Use of limits can greatly improve and maintain performance. Allowing for our Administrators to better plan for scalability, and improve maintenance schedules. End user’s clients will be more responsive and save storage space on their local computers. Plus the overall cost of storage is kept to a minimum.
Alternatives: SharePoint:
We offer SharePoint services for collaboration and document storage. Instead of sending out mass emails to all your coworkers, make an announcement on the SharePoint homepage for everyone to see when they login. Store your documents at your SharePoint site instead of saving them as attachments. This makes your documents accessible from Windows Explorer, which allows you to save your documents straight to the site from any Microsoft Office application.
Archiving:
If you archive your mail, the emails are pulled offline and stored on your local computer in a PST file. You can pick a certain date and everything received passed that date will be stored to the PST file. You can even setup an Auto-Archive schedule. They are still accessible in Outlook and can be opened in any other Outlook profile you might have. Also backup your PST to Disk to ensure your data is kept safe.
For more information on Archiving please visit,
http://office.microsoft.com/en-us/outlook/results.aspx?qu=Archive&av=ZOL110