Can an antivirus stop spam mails?

No, not usually. While spam is a pin, it is not malicious code. Therefore, antivirus programs will not usually do anything about them. There are some antivirus programs which do have a spam block feature, however. AVG is one program which offers this, but you may need to buy it to use the feature. I have found such things to be largely ineffective since spammers use different e-mail addresses every time. There are also some programs which are designed solely to stop spam, like MailWasher. They sometimes use pattern recognition to stop spam with the same content as other ones you have marked as spam. In any case, programs will only work if they are able to access your e-mail. Installing antivirus software with spam guard on you PC while you use Hotmail on the web will not help you. Some programs enable you to like them to web accounts. Others assume that the messages will come to you, being already downloaded by outlook or another program.