The answer is we do. We filter the mail coming into your jbntelco.com and giantcomm.net email account for most known viruses, and do a lot of junk mail filtering on the server side. Unfortunately, this is not enough to catch everything you can get from your email. That's why virus protection and a spam filter on your computer is such a good idea.
To help the spam filter improve, sign into the webmail at mail.jbntelco.com or mail.giantcomm.net. Click on the message you want to report, then click the "Report this message as spam" icon in the top right corner (it looks like a stop sign with an exclamation point in it). You can also move the email to the Spam folder in your email client if there is one.