"Send To" another mail client

[efla]

When I click "Send to", UR sends to Oultlook.

Is it possible to replace Outlook with another mail client, like Outlook express, or Thunderbird/Postbox ?

[$bill]

I'm not sure where in UR you are encountering the "Send to". I'll make a likely guess and suggest that it is a Windows default setting that you need to change to make Thunderbird you default mail client.
On Win 7-- Start | Default Programs | Set program access and computer defaults

http://windows.microsoft.com/en-us/windows7/Change-default-programs-using-Set-Program-Access-and-Computer-Defaults

[kinook]

http://www.google.com/search?q=make+thunderbird+the+default+mail+client

[efla]

I meant "Send.." in the UR File menu (and not "Send to", sorry)

Thanks for you tip, now it"s OK