Many organizations impose absolute limits on the size of mailboxes, especially when those mailboxes are located on a server. Allowing e-mail to grow uncontrollably can have detrimental effects, depending on which e-mail system you are using. In the case of Exchange 5.5 Standard edition, for example, Microsoft imposes an absolute limit of 16 GB for the private information store. If this limit is exceeded, the e-mail system will simply cease to function.
Even if you are using an e-mail system with no theoretical limit, it's still preferable to restrict mailbox size to minimize the possibility of corruption, not overburden the backup system or adversely impact the performance of the server. As a support tech, you may not possess the authority to impose limits or even to administer the e-mail server, yet there is still much you can do simply by influencing and educating your end users.
You must begin your fight against massive mailboxes by raising your users’ awareness. Send regular e-mails to all users explaining the situation in non-technical terms. Outline the impact of indiscriminately saving e-mail and specify what each user can do to help avert a crisis: delete, archive, move messages to off-line storage, and save attachments outside of the e-mail system. Make sure that you offer to assist in performing these tasks.
Target specific groups of users
Send more in-depth e-mails to groups of users defined by their e-mail usage. For example, if you know the marketing department regularly receives e-mails with large attachments, customize the messages you send them with more specific information about handling attachments. In general, the more users identify with the situation you are describing, the less likely they are to dismiss your suggestions as not pertaining to them.
Elicit managerial support when possible
Identify department heads, managers, or VPs who may be receptive to assisting you. Set appointments to explain the situation to them individually and ask for their support in educating and persuading their employees. If managers are cooperative but uncomfortable with technical concepts, offer to draft a memo for them to send out.
Identify difficult users
If some users don't respond to any of the above approaches, you may need to send personalized e-mails, pick up the phone, or visit the users at their desks. As this is a time intensive tactic, reserve it for your more difficult users who like to hoard mail or who have a hard time grasping computer concepts in general, or even for members of upper management who regard themselves as deserving individual treatment.
Schedule some IT department brown bag lunch sessions. Tell the users where and when you will be eating lunch and invite them to stop by and chat. Make it clear that these are informal sessions in which they can raise any computer-related concerns or questions they would like without having to go through the formal procedure for submitting work orders. Ostensibly you are there to answer questions, but inevitably the topic of e-mail will come up and you can use it as another opportunity for obtaining the users’ buy-in.
Arrange formal training sessions to teach the users how to manage their mail: Go over archiving, how to view the size of their folders, how to turn on junk mail filtering, and so forth.
Control incoming e-mail
Another approach to supplement these techniques is to attempt to reduce the amount of mail being received in the first place.
If your company permits the use of the corporate e-mail system for personal mail try to gain support from management for a policy to at least disallow saving personal mail on the server. If your company already prohibits saving personal files on the network, it would not be unreasonable to argue that this should also include e-mail.
If you don't have spam filtering in place, seek approval for making a purchase. Encourage users to send you the address of spammers they would like you to block. At a minimum, teach the users how to turn on and manage their own spam filtering on their client.
Take a cooperative approach
Whatever approach you choose to adopt, always remember that any changes, policies or limits you put in place must ultimately be for the benefit of the user. If upper management doesn't support your efforts, it is particularly important to adopt a cooperative and humble approach to asking people to use their already overburdened time to delete mail they would prefer to keep. After all, we cannot expect users to automatically understand the need for managing their e-mail boxes.