Couldn't create /home/usuario/mail (No such file or directory) + openwebmail

Hi, I recently installed Open Webmail and it works fine users that have /home/{USER} but those added to the system with the "useradd {USER} -s /dev/null parameter" it does not allow them to log in... givin the following mistake... Couldn't create /home/usuario/mail (No such file or directory) Any suggestions tommie -- ______________________________ msc. tomas alberto ramirez andujar sistemas de informaci'on y redes departamento de tecnologia educativa iplac - cel - la habana - cuba +537 274 14 79 - www.iplac.rimed.cu