Little correction Eddy… he speciafically meant on Yahoo web access…

Will it add the text at the bottom of an email thats done in Yahoo Mail on the web?

No, BBr|Ubergeek… it will not add signature at the bottom of your e-mails. avast! will add those signatures only in case you have access to your Yahoo e-mail account through pop3 (some of those e-mail clients like Outlook Express, Incredimail, Thunderbird etc.)