Applications :: Cannot Send Email - Keeps Asking For Password

I've set up various email accounts in Mail. I've had no problems downloading email but I'm cannot send emails. I can log on to my ISP's [Orange] Web Site so the password is correct. Everytime I try to send an email I keep getting a request for the password. I type in the correct password and Mail asks for it again and so on and so on.

My email address is <my>@<adddress>.wanadoo.co.uk.
Incoming mail server: pop.wanadoo.co.uk
User name: <address>.wanadoo.co.uk@fs
Password: <password>
Outgoing Mail Server:
Account Information
Description: left this blank
Server Name: smtp.wanadoo.co.uk
Advanced:
Use default ports clicked
Authentication: Password
User name: <address>.wanadoo.co.uk@fs
Password: <password>
Under Advanced I have set the:
Port: 110
Authentication: Password

I cannot see what I am doing wrong. In Outlook Express there was an option to enter yout smtp settings and then there was also a section for your ISP requires authentication. In that you would either click use the same settings or you would enter in different settings, if sending your mail through a different ISP. I also have accounts with other ISPs so would need to do same in Mail but I'm not sure how. Having said that, if I solve the current problem it would more than likely resolve the other one. I've tried pinging smtp.wanadoo.co.uk but nothing happens. However I can ping mail.btinternet.com so I know one of my ISPs works at least. Orange status line says the broadband service is working without any problems so unless that's false info, I'm doing something wrong.