I have been having problems with the space available on my account and it turns out this is due to a problems in my sent folder. My account keeps resending emails I have sent every few minutes and constantly?!

The other night I deleted all emails in my sent folder and it was 28,000. I deleted these but every day it is the same, my account is resending emails. Though the emails I have originally sent have been received the 'repeat' ones are not actually sent. They are like a 'ghost' email. Resending and showing in my account and space but not actually resent.

Anyone know how I can stop this? Please.....!