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Working out a new server for an agency of 200 Employees - with approx 240 email accounts.

Internally I'm arguing with myself over the amount of drive space to allocate to each user for the disk quota, I'm just looking for suggestions.

Once i have a quota size decided, it will define the solution for storage. I've had everything from 4 GB per account ( which i feel is being generous ) down to 500 Mb ( with is rather restrictive in today's day and age. ) Thing is 4 GB per acocunt is just under 1 TB of allocated storage for email alone.

Does anyone follow a "rule of thumb" or have thoughts on this?

thanks in advance

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I find that a lot of companies only consider the "hard cost" of backup and storage of email, and fail to account for the "soft cost" when employees use ad hoc email rentention systems like PST files and hardcopy to "get around" the imposed email quota policies. I have personal experience with a Fortune 500 company who set absurdly low email retention limits on their Exchange Server computers, but allows users to store email in PST files in their home directories on servers, creating a backup nightmare (goodby differential backups) and a legal compliance nightmare (eDiscovery request?). – Evan Anderson Nov 5 '09 at 15:39
I agree - We look at the cost of storage as just another cost of doing business. The quota's i want to set in place are not to lower my storage expense. just help define the initial storage provisioning. All of our users are configured with IMAP to the client or through web mail. This is specifically for portability as well as backup of email. Much easy to back up the source than rely on the users to back up their own email. – Ian H Nov 5 '09 at 15:51
up vote 1 down vote accepted

This is a "length of a piece of string" situation - it depends a lot on the amount of mail and the content of it (all small simple text messages, or do your users regularly send and receive large attachments?).

Your best bet is to have look at recent mail patterns for a sample of users, set your base quota by that multiplied by a small factor.

Two rules of thumb for mail quotas:

  1. One size does not fit all, so don't give every user in all departments 4Gb just because the users in the art/marketing department need that much for all the large images they transfer by mail
  2. Increasing a user's quota if/when they need it is a lot easier than decreasing it if they don't (they'll moan about losing something, even if they don't need it!) so set the quotas to a reasonable but not over-the-top value and make sure the server(s) send alerts (to the user, your mail admins, or both) when an account hits, say, 90% of quota.

4Gb is certainly too much as a general quota - I have over 18 months worth of mail in less than 256Mb on our current system (we kept the old mail server for archive purposes instead of migrating old data over) and I'm sure many people need less than I unless you are archiving mail for a long time. 1Gb is more realistic, but may still be too much as your base quota for everyone.

As well as considering the volume of allocated space for the live mail stores, remember that you need to allocate enough resource to backups of this data.

And if your users are sending large objects by mail internally (I've seen people send 10s of Mb to everyone in a company address book even though only a few people actually needed the documents), which could result in big mailboxes over time, you should at least consider encouraging them to use a more special purpose document sharing system - this might be easier to manage size wise, could allow useful things like revision/signoff control and other workflow helpers, and might be easier to backup in a way that makes restoring individual documents less work.

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Good point - a fluid quota or a flexible quota i guess is the option we will go for. We do have different requirements depending on the department. Leaving overhead to increase on the fly - thanks. – Ian H Nov 5 '09 at 15:38
I think it depends (comment on distributing large attachments internally) on how the space was used. I was told that Exchange will point to a common attachment on the storage side to give it to other users...if you have a user send a 40 meg attachment to 10 users internally, there is one copy of the attachment that they see (as long as it's not resent or altered) so it takes up 40 meg, not 400, on the server itself. Was that true? – Bart Silverstrim Nov 5 '09 at 15:52
That will depend on the mail server software and sometimes on how the software is configured. Like you suggest some mail servers will be bright enough to store only one copy of attachments sent that way, but certainly not all. – David Spillett Nov 5 '09 at 17:00

I've found that it entirely depends on your agency. If you have an environment where you can dictate policy and training, having a 2 or 3 gig mailbox is more than generous; you would need to keep at the users to get them to back up old mail and archive it offline to a storage area though for regular backups.

Make it larger and in some cases you'll have users that start using your mail server as a way to store all their documents, like an uber-convenient disk storage cloud.

If you don't have the ability to say "this is how it is", you're going to have administrator and people who outrank you dictate they want XYZ to work the way they want it to work regardless and probably will abuse it.

Do you have a mail system in place right now? What are the users currently using? What are the current statistics? That should form the basis of your estimates.

Usually if you set a big limit...5 gig,'re going to have a small percent who abuse it and will climb as high as possible, while most will use only a fraction of that space.

I'd look at your current usage patterns and see if you can get a rough estimate from that. Otherwise, get a terabyte of storage (if email is an important function, the cost of a good backup system and storage of a terabyte isn't much, even adding in RAID).

Last look at your data retention requirements. You don't say what agency this is for, but depending on the field there may be laws dictating what has to be retained and for how long. You'll need to factor that into your backup and storage strategy as well.

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Thank you all for your input. I think with the cost of storage being as low as it is setting my original thought of about 2GB er user will work. Data retention policies for our agency currently don't extend to email, but as we progress forward I know that it will. And yes, for better or worse I DO have the ability to dictate the way it's going to work. Thanks again – Ian H Nov 5 '09 at 15:35
We have retention issues that are being imposed legally since we're a school district, so it's not an internal policy thing as much as a state auditing thing. I didn't know if you were referring to a government agency where there may be laws dictating how far back email can be subpeona'd...either way if you have power to dictate, all the better. You can then periodically educate users on how to store data offline and have it backed up properly and not abuse the mail system. Good luck! – Bart Silverstrim Nov 5 '09 at 15:48

Well, several large companies (my current and former employers included) cap their employees to 100 megabytes with the theory that if the quota is low, users will more aggressively archive or delete what they don't need.

Of course, if you need to deal with many or large attachments, that's a bad solution.

I personally clean my mailboxes quite frequently, and rarely, if ever, get close to the limit imposed. However, for large-volume mailing lists, you could easily hit it in under a week.

You really need to look at current usage, and see if there's a valid reason to go with a large quota, in my opinion.

Make sure you know what (if any) data rentention regulations surround your line of work, too.

Another option, employed by the first college I went to, was to quota our network space. We could use those 500 megs for storage, email, assignments, or our website. But it was all one quota.

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Depending on just how email is being used at that agency you may find there are too many variables to just lock in one size for everyone. In my current position we have users who manage to keep their mailboxes to less than 100MB. There are others who cannot realistically keep theirs trimmed to less than 2GB+. I have it fairly easy due to the small number of users, currently about 25 with email accounts. What I've done is to monitor their mailbox sizes over the last year and use that as a guideline for setting individual limits. Not an ideal solution but one that works for us as it prevents users getting slack about their housekeeping.

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4gb upward. Email is not somethin to prune these days - my email folder goes back years and I use full text search quite often to find things. At the end of the day that is totally ridiculous low in cost - we do not talk of anything significant.

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