[CentOS] Yum - which repo did a package come from

Linux Advocate wrote:
> guys,
>
> i have installed mailscanner, spamassassin, etc on my machine. This was done sometime ago. Some of these rpms i got not frm centos repos.
>
> What command ( or yum command )  can i  use to find out which repo did this installled package come from.
>
> yum info packagename just says; 
>
> repo : installed
>
> i was hoping for something like repo:rpmforge or   something similiar. i have these 3 rpms which i cant remember where i got them from.
>
>
> dovecot-1.0.7-7.el5             
> mailscanner-4.74.13-2          
> spamassassin-3.2.5-1.el5
>   


rpm -qi usually says where a RPM is from, or who built it.