mass delete of spam

as far as i know you’ve got to in and mark them as spam one by one or delete them one by one ??

I have tried that and it sometimes hangs up my machine because there are so many

Put a check mark in the radio box for each spam, then click “delete all” from the bottom of the page. I find it difficult to believe Akismet missed over 1000 spam messages – or what you refer to as spam. I’ve used it for years and it never missed a single spam message/comment.