Last reviewed on February 8, 2015   —  No Comments

Note: As off July 2009, Outlook 2000 is “out of support”. This page is no longer maintained and is kept for reference only. Links on it may no longer work.

Outlook 2000 was included with all versions of Office 2000 (Standard, Professional, Premium and Microsoft Office Developer). It was also available as a standalone product; however, it doesn’t journal Office 97 application documents. Microsoft customers who have a valid Exchange Server client access license (CAL) can use Outlook 2000. Outlook 2000 is also included with Microsoft Small Business Server 4.5.

New & Improved Features | System Requirements | Versions | Patches | Problems | More Information

New & Improved Features

System Requirements

This is the official requirements list from Microsoft. If you plan to run other programs or use Word as your e-mail editor, we’d recommend more RAM:

  • PC with a Pentium 75 MHz or higher processor
  • Microsoft Windows 95 or later operating system, or Microsoft Windows NT Workstation operating system version 4.0 with Service Pack 3 or later
  • RAM:
    • For Windows 95 or Windows 98, 16 MB of RAM for the operating system, plus an additional 8 MB of RAM for Microsoft Outlook
    • For Microsoft Windows NT Workstation operating system version 4.0 with Service Pack 3 or later, 32 MB of RAM for the operating system, plus an additional 8 MB of RAM for Microsoft Outlook
    • For Microsoft Windows NT Server operating system version 4.0 with Service Pack 3 or later, 64MB for the operating system, plus an additional 8 MB of RAM for Microsoft Outlook
  • Available hard-disk space for Typical installation: 153 MB
  • CD-ROM drive
  • VGA or higher resolution monitor; Super VGA recommended
  • Microsoft Mouse, Microsoft Intellimouse, or compatible pointing device


Check the version number with Help | About. The version number is determined by the version number on the Outllib.dll file. This table lists the versions and the patch that updates Outlook to that version. Major updates are marked with the version number in bold:

Update Description Outllib.dll version
Original Via retail channels and as on the Exchange Server 5.5 Service Pack 3 CD. The Exchange SP3 version has at least one minor tweak, but does not change the version number.
Email Attachment Security Update This changes the way attached .exe files are handled when you try to open them from inside a mail message. The idea is to make it harder for something like the Worm.ExploreZip Virus to get through. Be sure to get the right version for your copy of Outlook.
IMO SPA Fix Fixes problem with IMO mode and Secure Password Authentication in which messages are not being sent immediately.
Attachments Forwarding Hotfix Fixes a problem in which Outlook was stripping attachments from forwarded messages under certain conditions.
Delegate Meeting Request Fix Fixes relatively minor problem with delegates not being able to distinguish between required, optional and resource attendees on meeting requests.
Calendar Folder Display Fix Resolves problem that can occur when a user accesses his or her Calendar folder via Outlook Web Access, then another user tries to open it with the File | Open | Other User’s Folder command.
Remote Mail Fix Fixes problem where Remote Mail downloaded headers for deleted items.
COM Add-in Toolbar Fix Resolves a problem that resulted in duplicate custom menu items on the Standard Explorer menu when a COM add-in is running.
Outlook View Control Fix Resolves access violation errors that can occur when you use the Outlook View Control from the Team Folders or Digital Dashboard kit on a machine that is also using an Exchange Client Extensions add-in that hooks into the Click event. Updates Outlrpc.dll, Mso9.dll and Lvreg.dll, in addition to Outllib.dll.
Microsoft Outlook 2000 Service Release 1 Major update with dozens of fixes for Outlook 2000, plus new security features to meet the requirements of the Defense Messaging System used by the U.S. government. Available both as download patch and on CD.
FTP Free/Busy Fix Fixes a problem related to publishing free/busy data via FTP through a proxy server.
Recurring Appointments Fix Fixes a problem with the Restrict method in programming code that can result in some recurring appointments not being retrieved.
Multi-purpose fix Allows custom forms to support copy, cut and paste commands. Also fixes several problems related to delegates and appointments. See:
Timeline View Fix Fixes a problem with the timeline view in public calendar folders not refreshing when grouped by Category.
Folder Home Page ActiveX Control Fix Resolves a problem with folder home pages that use unsigned ActiveX controls.
Outlook Email Security Update Extensive update to lock down many parts of Outlook that make it possible for a virus to use Outlook to propagate. Install with great caution, since it will change the behavior of some Outlook features and most add-ins.
XCLN Free and Busy Details Not Available When Viewed from Different Time Zones Fixes problem where Exchange Server free/busy public folder and Outlook clients are on different sides of Greenwich Mean Time.
Toolbar Fix Resolves several problems with toolbars. See:
Item_Write fix for Calendar items Resolves a problem that can prevent Outlook from shutting down after you drag appointments that use custom forms.
Multipurpose fix Allows you to change the default path for creating new Personal Folders .pst files and fixes a problem with RTF messages saved as drafts. See:
Multipurpose fix Allows Outlook 2000 Rules Wizard to correctly migrate Outlook 97 Inbox Assistant rules. Also fixes a problem with the Attachment Security Update and some later patches. See:
OL2000 The IMAP Client Side Rules Fail Allows Rules Wizard rules to work on IMAP folders in Internet Mail Only mode.
E-mail Security Update update Update to the E-mail Security Update to block Microsoft Access .mda and .mdz.
Post Reply to Drafts Fix Fixes a problem in SR-1 that causes replies to posts in public folders to save in the user’s Drafts folder. We don’t know yet whether it requires the Outlook Email Security Update.
Message Options One-off Fix Hotfix to prevent custom forms from one-offing when you set voting buttons or other message options. Includes the Outlook Email Security Update. unknown, but after
Office 2000 Service Pack 2 Major interim release to consolidate the E-mail Security Update, CDO Security Update and various hotfixes listed above, along with other fixes.
OL2000 The NewInspector Event May Not Fire For a Single Occurrence of a Recurring Appointment Hotfix to correct a problem with the NewInspector event that should fire whenever a new item is displayed.
Multi-purpose hotfix See:
CreateItemFromTemplate Fix Resolves an error that occurs with the CreateItemFromTemplate method.
Distribution List Programming Fix Makes it possible to add or remove contacts from a distribution list without displaying the list
Custom Meeting Request Fix Resolves a problem that can cause an error with customized appointment forms sent as meeting requests.
Multipurpose hotfix See:
Multipurpose hotfix See:
OL2000 Error Message The Name or Distribution List Has Been Deleted and Is No Longer Valid
OL2000 You Receive an Error Message When You Save an Appointment Item in the Calendar View
Multipurpose hotfix See:
Multipurpose hotfix See:
OL2000 Cannot Save Multiple Attachments to Long Paths
Multipurpose hotfix See:
You Cannot Receive New E-mail Notifications in Environments That Use the Network Address Translation Adds support for registry entries that force Outlook to use polling to check for new messages on the Exchange Server, rather than waiting for UDP packets.
Cannot Find Recipients Certificates Fix Resolves a problem with finding digital certificates in Contacts when the profile also contains the Personal Address Book.
Message Appears to Remain in Your Outbox When You Reply Affects replies to messages in a shared Exchange Server mailbox, if you have the save replies with original message option enabled.
Multi-purpose hotfix See:
VBA Events May Not Work After Print Preview Resolves a problem in which Outlook VBA code may not run automatically after a Print Preview operation.
You Cannot Receive New E-mail Notifications Affects computers using Network Address Translation (NAT). You must add a registry entry to set polling as the method for getting new messages, instead of UDP, which is the default.
OL2000 Message Headers Do Not Synchronize As Expected Corrects the behavior of Remote Mail against an Exchange mailbox to download only headers.
Forms Cache Refresh Fix Hotfix to add a registry entry that makes Outlook 2000 try to reload a form from the original published version if it can’t open the cached version. The registry fix looks weird, as if it were for Outlook 2002, but Microsoft assures us that it is correct.
OL2000 You Receive a Host not found Error When You Open a URL Link in an RTF or Plain Text Message
Multi-purpose hotfix See:
OL2000 Outlook Stops Responding When You Try to View a Calendar Hotfix to resolve a problem with CDO and recurring appointments.
OL2000 You Receive an Error Message If You Open a Public Folder That Has an OWA Page As the Default Home Page
OL2000 Contact Distribution Lists Display Incorrectly in Outlook 2000 Running on Windows 98
OL2000 Outlook Stops Responding with 100 Percent CPU If You Change the Language on the Taskbar Hotfix to resolve a problem with switching languages
OL2000 You May Receive Reminders Later Than You Should Hotfix to correct inaccurate reminder times.
Multi-purpose hotfix See:
Microsoft Office 2000 Service Pack 3 Major update adding customizable attachment blocking, better handling of forms cache corruption, and many fixes. All subsequent updates will require SP3.
You receive an error message when you select many Exchange 2000 recipients in Outlook 2000 Fixes an “operation failed” error that may occur when you select many recipients.
Outlook 2000 Update December 18, 2002 Fixes the problem in Outlook 2000 SP3 configured in Internet Mail Only mode where you may see CPU usage by Outlook go as high as 100% or get erratic reminder behavior. Does not update the version number because it fixes only Omi9.dll and Omint.dll. The version of both replaced files should be 5.5.3186.0. n/a
Multipurpose hotfix See:
OL2000 Cannot Display or Save Item Using GetItemFromID Minor public update to restore functionality to the GetItemFromID method, which SP3 broke.
OL2000 You Receive an Error Message When You Save a File Attachment Fixes a problem with saving file attachments, which SP3 apparently broke.
OL2000 Last Month of Other Persons Published Free-Busy Information Is Missing Ensures that Outlook publishes a full 12 months of free/busy information, not 11.
Unable to Update Free-Busy Data Error Message in Outlook 2000 Corrects problem that may occur if public free/busy information is deleted.
OL2000 A Digital Signature Is Not Added to Messages that You Reply to or Forward Ensures that a digital signature is added to replies and forwards when you have Always Sign turned on.
OL2000 How to Control the Unable to Update Public Free-Busy Data Dialog Box Adds a Please do not show me this dialog again checkbox to the dialog that appears when Outlook has a problem with background publishing of free/busy information.
OL2000 Category List is Blank Allows Outlook to support more than 700 categories or about 15,000 characters’ worth.
Multipurpose fix
OL2000 Unable to Display the Folder Error Message When You Click a Folder Home Page Link Resolves a problem with certain links on Outlook folder home pages.
OL2000 Shortcut That Is Removed from the Outlook Bar Reappears When You Restart Outlook Resolves an issue related to remove Outlook Bar shortcuts programmatically.
Outlook 2000 Post-Service Pack 3 Hotfix Rollup Package June 7, 2003 Includes all the above post-SP3 fixes, plus other post-SP3 fixes listed under Other Updates below, plus:
Outlook 2000 Post-Service Pack 3 Hotfix Rollup Package June 16, 2003 Includes all the above post-SP3 fixes, plus other post-SP3 fixes listed under Other Updates below, plus:
Outlook 2000 Post-Service Pack 3 Hotfix Rollup Package July3, 2003 Includes all the above post-SP3 fixes, plus other post-SP3 fixes listed under Other Updates below, plus:

Changes to Outllib.dll should be cumulative. However, patches often update other files as well. Just because you’ve installed the Delegate Meeting Request Fix doesn’t mean that you have the complete Email Attachment Security Update. If you don’t remember whether you’ve installed all the patches, it doesn’t hurt to install them again. Just make sure that you respond No when the setup program asks whether you want to replace the systems’ current version of Outllib.dll or Outllibr.dll with an older version.


Installing these patches does not affect the Outlook version number:

Update Description
CDO Security Update Updates the Collaboration Data Objects programming interface with the same level of automation security as in the Outlook E-mail Security update.
CDO Offline Synchronization Flag fix Post SR-1 fix for Emsmdb32.dll to fix an error that may occur when a developer uses CDO to set a folder for offline synchronization. Included in SP2
Defense Messaging System Hoftix Replaces the Emsmdb32.dll file to avoid a security prompt in Outlook 2000 with the Email Security Update. You can also solve this problem by adding a registry key.
GAL Contact Patch Fixes a problem that occurs when you add a Global Address List entry to Contacts and the name has an initial in it.
HTML Mail Vulnerability Updates Critical updates for Microsoft Internet Explorer to prevent harmful worms from entering your system via HTML-format messages.
OL2000 Outlook Sends HTML Messages to the Internet When You Use an Exchange 2000 Mailbox Hotfix for Exchange 2000 users who are sending text or rich-text, but recipients are getting HTML. Replaces Outlmime.dll.
IMAP Folder Switch Patch Replaces the Pstprx32.dll file to fix a problem where Outlook stops responding if you switch quickly between IMAP folders.
IMAP Thread Contention Fix Hotfix to replace the Omint.dll and Omi9.dll files to fix an error that may occur when you access moderately populated IMAP folders.
Java Permissions Security Update Tightens Java security to prevent malicious Java code from running in an HTML message. Requires the Outlook E-mail Security Patch or Office 2000 SP-2. If you don’t want to install SP-2, you can update the security settings manually by following the instructions in the article OL2000 Outlook Update for Java Permissions Security.
Outlook 97 RTF Compatibility Fix Provides better handling in Outlook 2000 for rich-text messages sent from Outlook 97. Included in SP3.
Outlook 2000 SR-1 Update View Control Security Update to the Outlook View Control used in Team Folders and digital dashboards to cure a significant security vulnerability. Requires Office 2000 SR-1/1a. Also see OL Developer Information About the Outlook View Control Security Update, and note that the changes do not affect how the OVC operates in an Outlook folder home page.
Update for “Malformed Header” and “Cache Bypass” vulnerabilities Update your system to protect Outlook against a vulnerability that can allow malicious code to enter your system, even if you do not open or preview the message. The update also eliminates a vulnerability that could allow someone else to read certain files on your system. See MS00-043 – Patch Available for ‘Malformed E-mail Header Vulnerability and MS00-046 – Patch Available for ‘Cache Bypass Vulnerability. All versions of Outlook are vulnerable, unless you use Outlook only to connect to an Exchange Server mailbox.

You have several patch options, depending on your system:

  • Install Internet Explorer 5.5, except on Windows 2000.
  • On Windows 2000, install Internet Explorer 5.01 SP1, available via Windows Update. Windows 2000 SP1 also apparently resolves this issue.
  • If you are already using Outlook Express 5.01, install the separate Security Update. To check your OE version, start OE, and choose Help | About Microsoft Outlook Express. If the version is 5.00.2919.6600 or, for Windows 2000, 5.00.2919.6700, you have Outlook Express 5.01. (Outlook Express 5.5 includes this update.)
  • If you are using Outlook Express 4.01 SP2, you can download and install the separate Security Update.
UPN Exchange Logon Fix Hotfix to replace Emsui32.dll and correct a problem with UPN (user@domain.dom) logons not working with Exchange 2000.
User-defined Character Set Fix Hotfix for users seeing empty To, Cc and Bcc fields on messages received via the Internet whose character sets are set as user-defined. Replaces Outlmime.dll and Pstprx32.dll.
Word 2000 SR-1 Update Mail Command Security Blocks possible unauthorized sending of messages through the plain text or HTML WordMail or “Office envelope” feature.
OL2000 Attachment to Signed E-Mail Message Is Missing When You Send the Message to a Public Folder Updates Exsec32.dll to fix a problem with attachments in digitally signed messages in Exchange public folders.
OL2000 Could Not Complete the Operation… Error Message When You Click Reply Patches Cdo.dll and other files to fix a problem with mail programs that use MAPI to display messages. Requires Office 2000 SP3.
OFF2000 Office 2000 Prompts You to Register After April 15, 2003 Replaces the Mso9.dll to correct a problem where, on April 15, 2003, some installations of Office 2000 began prompting users to register whenever they use Outlook or any other Office program.
OL2000 Outlook Quits with Error Message in Fm20.dll When Sending E-mail Using a Custom Form Post SP3 fix to replaces Fm20.dll and fix a problem with combo boxes on custom forms.
OL2000 You Cannot Change Your Password When the You Log On to a Non-Exchange Domain in Outlook 2000 Replaces various files to fix a problem with the password dialog. Requires Office 2000 SP3.

Known Problems

If you install Outlook 2000, but use Word 97 as your e-mail editor, when you forward a message with an attachment, the attachment is stripped. Either don’t use Word as your e-mail editor or upgrade to Word or Office 2000.

Installing the free Outlook 2000 standalone version for Exchange Server users, then later installing Office 2000 apparently causes problems such as losing forwarded attachments. If you’re going to install Office 2000, remove Outlook 2000 first.

See also:

More Information

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