Why won't Sylpheed send or receive?

Question

I have just installed Sylpheed but it neither receives nor sends emails.

1. I selected IMAP and clicked Forward.
2. Entered my email address ‘youruser@riseup.net’.
3. Give the account a name and clicked Forward.
4. Filled in ‘youruser’ and ‘yourpassword’ and mail.riseup.net (for both incoming and outgoing servers). 5. Select SSL/TLS for both.
5. Select Use SMTP Authentication. And clicked Forward. Got the email server – but not able to receive or send???

What do I need to do?