A user configures a new Microsoft Outlook profile by using an email address that resembles the following:
In this situation, the following error message is returned:
Cannot start Microsoft Outlook. Cannot open the outlook window. The set of folders cannot be opened. Unknown error.
Outlook uses the email address as the name for the data file, as in email@example.com. However "con" is one of the MS-DOS device driver names. Windows doesn’t let you use an MS-DOS device driver name when you create a file. The following is a list of the MS-DOS device driver names:
Keyboard and display
System list device, usually a parallel port
Auxiliary device, usually a serial port
System real-time clock
First serial communications port
First parallel printer port
Second parallel printer port
Third parallel printer port
Second serial communications port
Third serial communications port
Fourth serial communications port
To resolve this issue, use one of the following methods.
Method 1: Change the email address of the affected mailbox on the server side
Method 2: Change the name of the data file in the Outlook profile
To do this, follow these steps:
In Control Panel, open the Mail item, and then click E-mail Accounts.
Click Change, and then click More Settings.
On the Advanced tab, click Outlook Data File Settings.
Select the File name, and then delete the period (.) after the aux or con prefix. For example, if the file name is firstname.lastname@example.org - aux.user.ost, change it to email@example.com – aux.user.ost.
When you're prompted for confirmation, click Yes.
In the Change Account window, click Next, and then click Finish.