What message you get when the user can't connect?
Please check the report
System>>Reports>>Person list >> mark all companies
if you can see that user there and if that user is named or concurrent user and if that user is a named one, it has to have mailbox.
Mailbox for user is created in System>>Registers>>Persons>> select that person and click>> "Create" >> Mailbox
We do not do such support, for connecting to your system.
Please ask your partner if you want such service:
http://www.hansaworld.com/en/partners2/overview