Please contact your email account provider and ask them for these details:
- POP3 and SMTP mail server addresses.
- Port numbers for the POP3 and SMTP mail servers.
- Do you need to authenticate when sending mail?
- Do you need to use SSL?
Verify with them that the username and password that you are using are correct. In the IncrediMail main window, click the 'Tools' menu, select 'Email Accounts', select your email account and click 'Properties'.
Check that the details you have in IncrediMail are correct.