OpenDNS works well because it is not software.  With just a minor change to your home wireless router's DNS numbers you can be protected.
There is NO installation required on computers, iPads, etc. and all devices that connect through your router are protected.  Plus, it's free

Note: this is a website blocker but it's not a spam blocker.

How

1. Sign up here for OpenDNS Home.

2. Use these directions to change your router's DNS numbers to these numbers: 208.67.222.222 and 208.67.220.220
(You will need to know your router's admin password.  If you don't know it, it's probably still the default setting from the manufacturer).

(Usually you can browse to http://192.168.1.1  to adjust these settings)

3. Then go to the OpenDNS Settings area to configure the filtering settings you want. (see picture below)

When your IE browser starts acting strange there are two things you can do: Clear the cache and Reset your configuration

Clear your cache in Internet Explorer

In order to speed things up, browsers keep a local file cache of your recent sites. However, a stale cache can cause problems so use this procedure to clear it.

• Click on Tools -> Internet Options
• Under the General tab, click "Delete…"
• Under Delete Browsing History click “Delete”

Reset your configuration in Internet Explorer

This is a more drastic procedure that will bring you back to the factory defaults for Internet Explorer.

• Click on Tools -> Internet Options
• Under the Advanced tab, click "Reset…"
• Check “Delete personal settings” and click “Reset”

But most people will not read the message and will click the Yes button (especially since it’s the default).

Here’s how to suppress the message (So that No is picked by default)

1. Tools->Internet Options->Security

2. Select the ‘Security’ tab

3. Click the ‘Custom Level’ button

4. In the ‘Miscellaneous’ section change “Display mixed content” to Enable