[Dovecot] Problem in Mail receiving

i"m using dovecot-1.0.7-7.el5 on CentOS 5.5, i'm getting freqent problem of recieving multiple copies of mails received from outside my domain. this problem comes with some users and not with all the users, maillog shows the same mail downloaded again

Please help

Warm Regards, Anshul Chauhan "Never expect things to happen struggle & make them happen Never expect yourself to be given a good value Create a value for your own.."