Good parents always set limits for their children. A child may want to eat 20 cookies for dinner but the parent’s job is to say no, three cookies for desert is acceptable but 20 cookies could have some rather nasty side effects.
Just like a good parent, an email administrator needs to set limits when it comes to his or her users. Now I am not equating your co-workers to children, but you are responsible for the well-being of your users’ email so the metaphor does work on some level.
With Microsoft Exchange 2010, setting limits is relatively simple. Before you get started you should know that Exchange 2010 does set a default message size of 10MB for sending and receiving at a global level. But we all know that with 10MB people can get into quite a bit of trouble, especially when they save emails with large attachments in their inbox and refuse to move them to an alternate storage location. If you notice that your users are constantly complaining that they need their inbox size increased or you find that too many image files unrelated to work are being sent back and forth you can curb this by trimming down the message size a bit.
Open the Exchange Management Console and expand Organization Configuration, Hub Transport. Now click on Global Settings and then double-click on Transport Settings to bring up the Transport Settings Properties dialog box.
The first two settings, Maximum receive size (KB): and Maximum send size (KB): are what we are going to address first. By default, the numbers will read 10240 for both. This is the limit in Kilobytes, which equals 10MB. By changing it to 5120 you can set this number to 5MB and greatly reduce the file size of any messages being sent or received. Should a user try to attach a file that exceeds this limit they will be warned that: “The following files weren’t attached because they exceed the maximum size limit for attachments (5 MB)”. If the user tries to attach multiple files, say one that is 3 MB and another that is 4 MB, the first file attached will work while the other will receive the error message.
If someone tries to send a file, internally, and that message exceeds the file size limit for the recipient then the sender will be notified with: “The recipient won’t be able to receive this message because it’s too large.”
Keep Senders In Check
Looking down the list of limits you can set, you should also see the Maximum number of recipients: line. This is a great way to help keep your servers off the DNS block list. By limiting the number of messages that a person can send out at one time can help prevent an overzealous marketing campaign or newsletter from looking like spam to everyone else. Simply take that 5000 default and give it something like 1000 to help control what leaves your organizations mail server.
Likewise, you can try to force users to store emails in a location other than their inbox by reducing the Maximum size per mailbox database (MB):. Taking this down a few Megabytes will cause people to move larger email messages to local or network folders in order to keep their inbox small enough to receive messages.
Things to Keep In Mind
Some of the examples used in this tutorial may not be wise to use in all organizations. Setting send and receive limits that are too small could cause normal business processes to be held up because communication is not happening. Likewise, setting a mailbox size that is too small will definitely result in a number of support calls to the email administrator requesting a size increase.
Before setting email limits, make sure that you have discussed the changes with the different departments in your organization and you have buy in from management to do so. The last thing you want is for a senior level executive to wonder why he or she can’t send or receive emails because they weren’t aware of your changes!
I encourage our readers to share some of the limits they set for their users so that people can use their examples to find the right size limit to set.