Migration troubles

I am attempting to migrate two email addresses from a xeams server running on a linux box. The migration connects and lists the imap folders, the number of emails in each folder but does not proceed to importing/migrating the listed emails. I can import only the INBOX folder if I try to connect with pop3. I really need this to work. I have the pst file from outllook for each imap account. Can I please have the tool to use that PST file to import?