Spam e-mails

Over the last couple or three weeks I have been getting unwanted e-mails and NIS has classified them as Spam.

These e-mails are annoying and are coming in daily, I live in the UK and they are of American origin.

I know that because of the spelling of certain words.

Is there a way that NIS can block them at source without having to input names and e-mail addresses. The last thing I want to do is inadvertantly open them to put the e-mail address in to block.

All the e-mails are from different persons and all different addresses but I suspect from the same source.

Can anybody help on this issue.

Deric