deleting 'sent message' Folder

[Sue]

I am unable to delete my very large 'sent message' folder. My trying to
delete individual messages in the folder - my delete will not work. In
addition, my messages in my "In Box' will not delete either. Any advice on
how to remedy this? Sue

 

[Ultraglide]

Did you try moving them to the "deleted items" folder and then empty that?