Mail not working in CRM

I'm having difficulty getting a user setup with email for our domain. Mine (the administrator) appears to work just fine. However, the other user is not getting email sent to her address at the domain.

I've noticed that by name appears followed by the correct email address in the folder frame on the left of the screen. Hers shows her zoho.com email address. When I check the Mail settings, My domain email address shows the option of "Edit" only, where the Zoho.com and another I have configured show the delete options. The other user does not show the "delete" option at the zoho.com address - only the other two.

I have sent the default email id as my registered domain. Something is not clicking.

Also, I have configured the POP3 mail for another account yet the mail is not delivered to any of the zoho mail accounts.

I have come to the end of every possibility I can think of. Any help would be appreciated.

Grant