Quite a few of your tips discuss options in Outlook that can only be configured in the Registry.
I see things then like Key, Value name, Value type and Value.

How does it work exactly and what should I do with those values?

Lately, all my attachments are being received as gz-files. For instance a Word document comes in as a .docx.gz file instead of a .docx files.

How can I can I receive my emails normally again with their original extension?

When I try to delete a folder or move a folder, I get;
“Cannot Move The Items. The Folder is Full”.

If I try to rename a folder, I get:
“Cannot rename ‘<new folder name>’. The Folder is Full”.

I get this even with folders that have nothing in them.

Permanently deleting (SHIFT+DELETE) doesn’t work either and results in the error;
“The message interface has returned an unknown error. If the problem persists, restart Outlook.”

How can I get Outlook back to work again?

I’ve created my own Stationery with a background which I would like to use for my messages.
How can I add it to Outlook so I can select it?

I got an error in Outlook which said to look in the Sync Issues folder for more details.

Where is that folder located?

I’d like to add a watermark to my message which says “confidential” as an extra visual reminder.

Does Outlook hold such an option?

I have my company’s website address in my signature and it should be blue and underlined.

However, it shows up purple. In the editor it shows as blue and even when I recreate it, it shows up as purple again.

How can I make it stay blue?

Is there any way in Outlook 2007 to get reminded more visually that my Out of Office is still on?

When opening Save and Open dialogs in Outlook (and other Office applications), there is a space on the left with some default locations.

How can I add my own locations?

We’re using a shared Public Folder to organize our project in. This foder is buried quite deep in the Public Folder hiearchy and I need to access it several times per day.

How can I quickly access it without needing to browse to it every time?