emails won't delete

hey all. I'm curious. I've got kmail/kontact set to delete my emails after a 
set number of days and neither one will do that. I create a POP3 account with 
all of the credentials and I've still got email on here from a couple days 
ago. What do I need to do to alleviate this issue? Thunderbird does this 
really well and I want kmail to do the same thing. Should I create an IMAP 
email account to handle this feature better?
-- 
Charlie Luna

Ubuntu California Loco Team member
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ubuntu-california.org