HTML signatures in Outlook 2013 or Outlook 365 no longer convert and embed pictures. Instead, a URL to the picture source is used.  The result is, though all looks well when composing a message, the recipient won’t see the picture unless it is online somewhere and available via a standard URL.  Locally stored and referenced pictures will not be visible because, to the recipient, a reference to the sender’s C drive means nothing.

To revert to the behavior of previous versions of Outlook, where images are converted and sent with the message, add the following registry key:

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Options\Mail
Value type: REG_DWORD
Value name; Send Pictures With Document
Value: 1

1. Log into the server and press Windows key + R then type MMC.exe.
2. Click on File > Add/Remove Snap-in > click on Group Policy Object > Add> Finish > OK.
3. Double click on Local Computer Policy > double click on Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Connections.
4. Limit Number of Connections = 999999.
5. Restrict Remote Desktop Services users to a single Remote Desktop Services session = DISABLED.