Microsoft

10 reasons to avoid using PST files

The use of Outlook's PST data files have the potential to cause serious problems from data loss to compliance issues.
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PST files are Outlook data files that are sometimes used as a mechanism for message archiving or for avoiding mailbox quotas. Although PST files can be handy, it is best to avoid using them in your organization if possible. Here are ten reasons why.

1. PST files are rarely backed up

PST files typically reside on workstation hard drives or on removable storage devices. In any case, the PST file is unlikely to be backed up because most administrators do not backup workstation hard drives. This of course can lead to data loss.

2. There may be compliance issues

Every organization has sensitive data that they do not want leaked to the public. Sometimes this data is company confidential, and in other cases there may be regulatory issues describing the proper handling of the data. In either case, the use of PST files makes it far too easy for sensitive data to walk out the door.

3. PST files are prone to corruption

One of the big problems with PST files is that they are prone to corruption. The original PST file format had a 2 GB size limit, and corruption would occur if the file grew beyond its limit. Modern PST files are less prone to corruption, but can still be problematic. This is especially true for PST files that are stored in locations where they might be accessed by more than one user at a time.

4. They make e-discovery more difficult

Data that is stored in a PST file exists outside of the Exchange information store. As such, PST data is not analyzed when you use the native Exchange Server e-discovery tools. There are third-party e-discovery tools available that can analyze PST files (assuming that the tools have access to the files), but there is no question that the use of PSTs complicates the e-discovery process.

5. Network-connected PSTs are not supported

It was previously stated that PST usage can be problematic due to the fact that PSTs are often stored on workstation hard drives or removable media, and therefore do not tend to be backed up. Unfortunately however, Microsoft does not support storing active PST files on network shares. Placing an active PST file on a network share increases the odds that the file will become corrupted (at least that’s what Microsoft has always preached).

6. PST files are local to a device

Today it is common for users to access mailbox data from a variety of devices. They might access their mail from a PC while working at the office and from a smartphone while on the go. However, PST files are device specific. If Outlook stores data in PST files then the data will only be accessible using that copy of Outlook. The data will not be accessible to any other device that accesses the corresponding mailbox.

7. PST files only work with Outlook

Another disadvantage to using PST files is that they only work with Outlook. Mobile devices that attach to Exchange mailboxes using ActiveSync cannot open PST files. Similarly, Outlook Web App does not include any support for PST files.

8. PST files can be used to circumvent message lifecycle management policies

Some organizations put policies into place to regulate message lifecycles. For instance, an organization might automatically purge messages of a certain age. The idea is that once a message is old enough that the organization is no longer required by law to keep a copy then the outdated messages can be purged to keep them from being subpoenaed in the event of litigation. If a user stores old messages in a PST file then they have effectively circumvented the message lifecycle management policies. Doing so may eventually put the organization at risk in the event that the messages are ever subpoenaed.

9. Shared PSTs are problematic

I mentioned earlier that PST files were sometimes prone to corruption. One thing that is known to greatly increase the chances of a PST file becoming corrupt is sharing a PST file among multiple users. This is especially true if two users simultaneously attempt to open the same PST file.

10. PST files increase the cost of doing business

PST files have a tendency to increase the administrative burden. Administrators might be asked to discover PST files across the organization, or a user might ask an administrator to try to recover data from a corrupt PST file. In either case, there is a cost associated with the extra administrative effort. Likewise, there might be costs associated with data loss or inappropriate data exposure.

32 comments
bermudamohawk
bermudamohawk

Lack of pst files reduce the need (once again) for IT support. 

Pretty soon, you won't need any support at all.

agustin.moya
agustin.moya

Ok, we know why no, now. What's the solution?

SpiritualMadMan
SpiritualMadMan

But... There is a very good reason to use a local PST file...

You can access your email when the !@#$% network or server goes down.

Having experienced data loss due to server issues, and never having experienced data loss locally...  Perhaps I am lucky... I also trust my own back-ups more than the net admins! 

Lastly, some of my projects are multi-year and the network policy on deleting old e-mail with a rigid one sixe fits all sees project information deleted on a regular basis...

Of course... After the debacle with the obummercare site... What else should I expect from an givernment network??? Especially a military one!

Not a happy network user... Which tops my list of reasons to leave my current employer *if* the job market ever improves...



danos
danos

You haven't told us anything! I think you are repeating yourself, practically on each paragraph. And you haven't told us what one should use instead. Most companies and organizations use Exchange and Exchange doesn't use PST. Furthermore CACHING the Outlook data on the local workstation an .OST file is created, which is an additional security in the event of an Exchange Server crashing and there are no backups (highly unlikely). Furthermore, if an individual uses Outlook on their computer, the same e-mail address may be used on an iPhone (or similar), so there is still no problem even if the PST file crashes. Furthermore Microsoft has provided in the Outlook installation a repair function for the PST file. Apart from the fact there are many other third party programs that may be used to recover/repair a PST file!  So, where do you see the problem and why all the fuss??

pa79th
pa79th

So, what are we supposed to use as the alternative?

alinawaz83
alinawaz83

+1, any other alternate.... to secure data

Jim Johnson
Jim Johnson

I have about 8 years of stored Outlook data. Incoming data is moved into appropriate folders via rules. I keep several archive files and designate in Outlook which folders are archived to which archive files. Plus I periodically compact my primary.PST file. Outlook stays happy and fast.

As for multi-system access, IMAP takes care of that for accounts where this is necessary.

woofcubatl
woofcubatl

The only time I have ever really seen corruption in PST files is when the PST file was abnormally large and something goes wonky with a upgrade to outlook or the hard drive has issues. Although terrible when it happens, thankfully it has only occured a handfull of times. There are decent PST repair programs out there that will recover most if not all and repackage it back to PST format. I tend to like the open source approach to email software. Evolution is fantastic and supports exchange. I believe it even allows importing PST files but I could be wrong. Not to mention free from the licensing nightmare that is MS as well as Apple's approach. I understand that open source alternatives arent always feasible in the Enterprise, although often overlooked as good alternatives for a number of reasons and personally I feel are more stable to run than outlook.

Gisabun
Gisabun

Seems that Mr. Posey is living in the past [say 10 years ago] when PST had issues when exceeding 2GB in size. I've seen people with 10+ GB and no issues.

If you compress the PST every once in a while it improves the performance and reduces any chances of problems.

I've have used Outlook on my home system for over 12 years. I keep it "lean". Projects I work on are in a separate PST and are "disconnected" from Outlook when done.

As of Office 2010, PST files are stored in My Docs. easy to find. Microsoft doesn't support PST file usage over a network but that doesn't mean you can't. If you have a stable network shouldn't be an issue. even then, how hard is it to copy the PST over to a network folder?

Compliance? There is an option to disable the feature to create or use a PST file.

Anything better out there? Windows Live Mail is crap. Even harder to backup as each message is a single file. Try backing up 35,000 messages.

PST are forward and backwards compatible in Outlook. So I can use my PST in any version.

Why duplicate things. #3 and #9 are almost identical. So are #1 and #10.

alexisgarcia72
alexisgarcia72

I have 10+ years working with psts. No issues at all. I know archive is the best practice but not all companies have budget for that. I have about 800 GB of pst backed up in hard drives and dvd disks. Again, no corruption, no issues, no problem by saving pst files in network drives.

Darren B - KC
Darren B - KC

PST's are more versatile than this misinformed article would have you believe.  I manage about 750 GB of PST files covering over 50 users and in 7 years of creating them, backing them up, moving them, connecting to them (even over a network), I've yet to encounter a single case of corruption in a PST file.  I have quite a few PST's that are over 6GB each, and there's nothing wrong with them.  (For the record, I encourage users to keep them under 4GB so they'll fit on a DVD for backups.)

#6 is just plain wrong.  I can connect any copy of Outlook to any PST, regardless of which copy created it.  Where does that BS even come from?

Connecting to a PST on a network share works perfectly fine, but as a general rule, I only allow this if the user is simply reading from it, and not adding any new email to the PST.  I have several users that are connected to a large number of network PST's and again, no corruption has ever occurred.

Khulud Habaybeh
Khulud Habaybeh

offline every 2 years pst , starting new then act with as the regulations require

dspernow
dspernow

This article appears to be an advertisement from Microsoft to use Exchange. Not every business can afford Exchange and PSTs have been in use a long time with a good track record. PSTs on a network share work just fine making backup a snap. And who share's PSTs? ACLs restrict! Outlook can be configured to support email retention on server and allow mobile device sync/web access to downloaded email. Outlook can also be configured using Group Policy, including PST sizes for addressing mailbox quotas. Using PSTs places the burden of message management on end users. Organizations wishing to control message management should probably opt for Exchange.

Brian Wolters
Brian Wolters

My company pays like $30 a month for POP3/IMAP email with up to 100 mailboxes. I've suggested Exchange Online a few times but would raise it to about $250 a month. My boss is onboard but doesn't want to present it to the owner for now. So for now, we rely on PST files and archives. I backup management's PST's every Friday night.

MemphisDan
MemphisDan

This is a good list of reasons not to use the pst file for message storage; but it would have made a great article if it provided some alternative solutions. Why list all the problems with no solutions? Don't curse the darkness if you can't turn on a light.

Lars Larson
Lars Larson

The larger they become the more likely they will become corrupt.

Nathan Weber
Nathan Weber

The files are almost always inconveniently humongous.

bsalloum
bsalloum

Several users in my organization has used pst files on network shares for several years without issues. They are automatically backed up as part of our regular network backup routine. As a laptop user, I have chosen to keep my pst file in my local HDD, but make use of Microsoft's free PST file backup utility to back it up regularly to our network. With the old 2Gb limit, we did experience occasional corruption when they reached maximum size. However,  the 20Gb limit, teaching users to keep their contents cleaned up, and making use of autoarchive has rendered all of this a non-issue.

bnicholson
bnicholson

I have been coming around to this way of thinking over the past few months, but have been very unsuccessful finding a POP software package that is as universal as Outlook. There are a couple, but the best known, Thunderbird, has stopped development other than security issues. My old favorites have been out of development for years. I am trying hard to divorce myself from web-based e-mail.

 I want something that I can have my mail on a Windows, Mac, and Linux platform with a drag-and-drop datastore. That would have been a nice add-on to this article.

CharlieSpencer
CharlieSpencer

Assuming that's all true, what do you suggest as an alternative?  Exchange mailboxes with no size limits?  Saving messages as individual files? You still have the proprietary issue, and that just shifts the administrative burden from one hand to the other.

I've never had an problems with single-user .PSTs in a 'My Documents' that was redirected to a network share.  That takes care of the local storage, no backup, data walking out the door, single device, and sharing issues.  It may not be supported, but it seems to work.

Hengky
Hengky

@Jim Johnson I did that too and it's way easier and simpler to manage. The PST corrupt cases is rarely unless the PST files is exceptionally large. If PST is compressed and well managed and backup, I don't think there's any problem using them as a form of email backups.

danos
danos

@Gisabun Couldn't agree more with you. Windows Live is a ":glorified" version of Outlook Express, which definitely problematic in more than one way. As for the PST size, I have seen a 16Gb PST file that is still going strong - well in a manner of speaking! Yes, it is vulnerable at that size. Microsoft gives a max of 18 Gb for a PST file.

jball480
jball480

@Gisabun 

We use PST files over our network without any issues. Occasionally the user will have to disconnect and then reconnect the PST file back to Outlook if they haven't used the file in awhile but I don't call that an issue. On the other hand I've experienced corrupted PST files because of the size limit however W7 has fixed it every time without an issue.  

DAS01
DAS01

@Gisabun On what basis do you think Windows Live Mail is "c***"?

I recently migrated to it from Outlook Express (on the way to Outlook 2010 but decided to stick with it, partly because of some criticisms of Outlook voiced in MS forums).  Interface is fine for my purpose, though I miss OE's ability to copy and paste the whole message, incl headers, into a text app like Word or Notepad.

(It seems no modern mail client allows that - you need to click on Reply or Forward to be able to highlight the headers.)

BTW, having each message as a separate file is actually much better for professional backup systems, especially those that do delta blocking (incremental backups).

So, what is really wrong with Win Live Mail?

Darren B - KC
Darren B - KC

@Lars Larson What qualifies as "larger"?  I've got some user PST's that exceed 8 GB and they've used them for a long time (years) without corruption issues.  So, I'd just like to know what the size-to-likelihood-of-corruption ratio is.

Gisabun
Gisabun

@Nathan Weber : Well duh. That's all your Email in one file. You think Outlook throws a few MB here and there extra for each message?

CharlieSpencer
CharlieSpencer

I'm not a big fan of autoarchive.  Users tend to passively let it archive everything, including 'Out of Office' replies, jokes, delivery / read confirmations, multiple copies of the same messages and attachments, etc.  Leaving it off encourages users to actively select what to keep and what to trash, instead of delegating that decision to a utility that isn't going to make any choices at all.  Sure, they can still drag and drop everything to the archive, but there's a better chance they'll look first.

Tiger-Pa
Tiger-Pa

@CharlieSpencer 

I totally agree with you about single user PSTs except with users that feet it's necessary to save everything as a way of CYA, and saving all large attachments as well. Even so I only recall one time of trying to recover data from a corrupt PST.

To this day I still keep my home PST(s) including an Archive PST on one of my NAS drives so I have the same profile regardless of which PC I access it from. It may be true that Microsoft formally does not support networked PSTs; yet still allow the configuration to be accomplished easily, even with Outlook 2013 (Office 365) running on Windows 8.1 connecting to a POP3 server.

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