Website sending spam

Hi,

I recently received an email from my host that says my website has been sending spam. I have lost contact with the person who did my website and I was wondering if there is anything i can look out for to rectify this issue on my own.

This is what the email said:

This is to inform you that your site has been sending huge amount of spam mail. This is usually caused by a vulnerability on your site, causing people to use some of your site forms to launch a spam mail attack.

Attached below this email are the logs with regards to the matter.

To prevent further abuse, we have moved(renamed) the folder away from its original position:

[HOME]/public_html -> [HOME]/public_html.moved