Mac Mail problem

I have recently bought a macbook pro to run my business from, but I am having some mail problems. I am trying to set up my mail accounts and having password problems when it comes to IMAP. When I try to create my account and get to the user name and password part it tells me I have the wrong user/password (IMAP password). It makes no sense I have searched the forums and deleted all my keychains. I wasnt having this problem until I tried to add my second IMAP account. I have deleted all my email accounts and tried from step one, but now I cant even create 1 with this problem. Justhost is hosting my email accounts aswell. I have checked their forums and also nothing. Any tips or solutions would be great as I am new to mac itself. Thanks

Regards,

Liam