Updated to OC 2.2.Now marketing email (Newsletter) does not work

Recently updated to OC 2.2. Now there is a bug with the email function under Marketing. No matter if I choose to e-mail All Customers or a certain customer group the emails starts sendning as they should, but then randomly just stops with message "success 680 out of 3000 were sent".
I use the standard mail set up, not SMTP. Checked that all is correct. I've searched and found topics on this from other users in the past, but no solutions at all. As we have thousands of contacts in our data base it is essential that we get this to work again. Anyone knows what to do?

Ask you hosting provider if your are allowed to send so many email.
On my servers a account is not allowed to send more than 100 hourly.