Fastmail migration tool unable to migrate inboxes from godaddy "business" email
 

Nor can Imapsize etc.

Godaddy are a real pain.

If IMAP is not supported (a rare issue these days) it should be possible to download messages from the Inbox using POP.

Would you need a Fastmail application password, like you do when you set up your phone.

Surely, the answer would be yes. Only when signing in using a browser can you use your main account password.

It is imap, the other folders work fine.
I think it is godaddys way of making it very difficult for ordinary people to move away.
A bit like their convoluted domain management screen which makes it very difficult to transfer away.

https://www.godaddy.com/help/imap-set-up-email-4714

What error message did you run into when you tried to use IMAPSize?
It hasn't been updated since February 2009. Have you tried a email client like Thunderbird or eM client?

I was just checking to see if he was using an application password.

Also you have to select the correct box with F/m for IMAP other wise it wont work.