Have wlm on pc 1..all ok

In addition have now loaded wlm onto another pc, pc 2..BUT it won't stop downloading ancient email messages onto pc 2
..I deleted them all.. and same thing...
...6,500 nessages downloaded dated between 2011 and todays date downloaded onto pc 2!

What I want to do is delete all old messages on pc 2 and start using wlm on pc 2 with new messages only as from today.
Any advice appreciated.

My internet provider is gofast.co.uk if relevant.