I've tried and failed to setup 3CX mailing [e.g. for 3CXPhone clients etc.]. I am running 3CX version 12. I have used the following: smtp.tools.sky.com on port 25 with SSL/TSL ticked - Get the Error: Server does not support secure connection. with SSL/TLS un ticked - Get the Error: SMTP requires a secure connection....The server response was: 5.7.1 Authentication required. I've tried entering: smtp.tools.sky.com:465 [which is the correct port I use with Outlook] The sending email box in 3CX stays onscreen for ages and then, I get the Error: Failure sending mail. Unable to read data from the transport connection net_io_connectionclosed. I've also tried the above settings with smtp.live.com as well. Does anyone have any advice or could suggest an external smtp server that would work with port 25 and SSL/TLS. I'd rather not setup an internal smtp server.