The outgoing mail server needs to be smtp.tools.sky.com - you have it as pop.tools.sky.com (at least from your post above).
On the Outgoing server tab, select the 2nd option - i.e. 'Log on using' & enter your Sky details.
On the Advanced tab, Outgoing server (SMTP) needs to be 465, & put a tick in 'This server requires an encrypted connection (SSL).
More details at click here. The only ones not to use (for the Orange email account) are the incoming server settings. G