DisableOffice365SimplifiedAccountCreation

Outlook from Microsoft 365 (Office 365) has a simplified Auto Account Setup wizard, the option to manually create an account no longer appears. However, there is a possibility to make the Outlook option for manual account setup available anyway.

1. Close Outlook if it is already open.
2. Next, open Registry Editor with the Windows+R keys and type regedit and click OK.
3. In Registry Editor, navigate to the following key: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Setup
4. Right-click to open menu and click New to select DWORD (32-bit):
5. Rename the new DWORD key with the value : DisableOffice365SimplifiedAccountCreation
6. Double-click the new key to change the value.
7. In the field, enter a value of 1 and click OK.
8. Close Registry Editor and restart Outlook.

It is also possible to activate the Outlook option for manual account setup do perform the REG ADD command.

To do this, open a command prompt with the key combination Windows+Rcmd and click OK.

Insert the following line in the command prompt and press Enter.

REG ADD "HKCU\SOFTWARE\Microsoft\Office\16.0\Outlook\Setup" /v "DisableOffice365SimplifiedAccountCreation" /t REG_DWORD /d "1" /f

Start Outlook and select Manual setup or additional server types.

Outlook limits the default size for PST Files and OST Files to 50 GB. The size is determined by the registry value in the registry, the maximum can be increased to about 4 PB (4096 TB).

In Outlook 2003 and Outlook 2007, the maximum recommended size of a PST Data File and an OST Data File was limited to 20 GB.

Outlook 2010, 2013, 2016, 2019, and Microsoft 365 set this recommended limit to 50 GB.

How to increase the maximum file size of a PST Data File ?

To increase the maximum size of PST files and OST files in Outlook, the values must be created and set under the following key in the registry.

Outlook 2003
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\PST
Outlook 2007
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\PST
Outlook 2010
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\PST
Outlook 2013
HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\PST
Outlook 2016 / Outlook 2019 / Microsoft 365
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\PST

Increase Size of Outlook PST Data File and OST Data File

The following 2 new DWORD values must be created or set, to increase the Outlook Data File limit.

• WarnLargeFileSize
  Do not set this higher than 4090445042 (decimal) or f3cf3cf2 (hexadecimal)
• MaxLargeFileSize
  Do not set this higher than 4294967295 (decimal) or ffffffff (hexadecimal)

Run REG ADD in Command Prompt

Opening a command prompt by pressing the Win+Rcmd and run the following two lines.

REG ADD "HKCU\SOFTWARE\Microsoft\Office\16.0\Outlook\PST" /v "WarnLargeFileSize" /t REG_DWORD /d "4090445042" /f

REG ADD "HKCU\SOFTWARE\Microsoft\Office\16.0\Outlook\PST" /v "MaxLargeFileSize" /t REG_DWORD /d "4294967295" /f

Lines with Copy Paste run in the Command Prompt.

The first value WarnLargeFileSize indicates how many MB a user can write to a pst or ost file before receiving a warning that the file is full.The second value MaxLargeFileSize indicates how many MB the system can write to a pst file or ost file.This value must be at least 5% higher because more than just user data is written to a pst file and an ost file.

  Although the registry path is PST, it also applies to OST files.

  If the mailbox is on an Exchange Server or an Office 365 account, the quota must also be increased.

  In Outlook 2013 and earlier versions, IMAP accounts also used an Outlook Data File (PST). Starting with Outlook 2016 and Outlook for Microsoft 365, IMAP accounts use Offline Outlook Data Files (OST).

Outlook offline data file (OST)

Most account types, e.g. Accounts such as IMAP accounts, Microsoft 365 accounts, Exchange accounts, and Outlook.com-accounts use an Offline Outlook Data File (OST) to keep a synchronized copy of your mailbox information on your local computer.

Outlook Data Files (.pst) created using Outlook 2013 or Outlook 2016 are usually stored in the Documents\Outlook Folder on the computer.

Offline Outlook Data File (OST) from Outlook 2019 and Microsoft 365 is saved under %LOCALAPPDATA% under the path \Users\Username\AppData\Local\Microsoft\Outlook. Most of the data remains on the server. However, all locally stored items should be backed up. For example, Calendar, Contacts, Tasks and all folders are only marked as Local.