There's no fix from Microsoft, if indeed this really needs fixing; however, there's a third-party plug-in that provides this functionality for free. Programmer and computer science PhD grad student Emil Stefanov created an application he calls Outlook Email Notifier (OEN), which creates the envelope icon in the system tray for IMAP accounts. You can download the application from Stefanov's website.
The small setup.exe file installs a .vsto file. You can install this plug-in while Outlook is open; however, Outlook will require a restart to recognize the addition. You can identify the plug-in within Outlook 2010 by navigating to Tools, Options and selecting Add-Ins. Figure 1 shows that the Outlook Email Notifier plug-in is installed.
There's no actual UI for this plug-in; it has a very simple function: You'll now see an envelope in the system tray for new email messages, including new messages received on IMAP accounts. The envelope is a little larger than the envelope you typically see in Outlook. If you have only an IMAP account, you'll see only the OEN plug-in rendition of the new mail envelope. If you have an IMAP account plus another account type, you'll see multiple envelopes as shown in Figure 2. The slightly larger envelope is displayed by the OEN plug-in.
If you're using Outlook 2010 on Windows 7, there's another mechanism to view the new mail envelope. The Windows 7 taskbar shows icons of applications in use. When new mail arrives in Outlook 2010, the Outlook logo icon changes to include a little envelope overlapping the icon. Figure 3 shows the Outlook logo in the Taskbar, and Figure 4 shows the same logo after new mail has arrived for that profile. In this case, the envelope shows regardless of what protocol is in use for the Outlook account.
Overall, this little Outlook annoyance does have options for those who are using IMAP and simply must have the little envelope in the system tray to identify new email.