Check the SMTP settings within Outlook if thats what ur using.
POP3 will be ok, if u can receive.

You havent changed Dial up provider have you, or gone from broadband to dialup, as this will create an issue. You NEED to use the same dialup/broadband as your email address is with. You can receive from any provider, but to send, the connection must be initiated with the ISP you have the email with.

Its security issues yasee

Alternatively, I'm off work on Fri/Sat so can pop down and have a look if u want mate