[otrs] cant get emails to go into otrs

[DataForce CRM]

I have read the documentation and set up my mail server and the pop 3 in otrs. I just can not get emails into OTRS. 

Is there a mail server that OTRS uses on the OTRS server that I can check to see if running? 

Can someone suggest checkpoints I can go over to see where I went wrong? 

Thank you. 

JR