Sending and reading e-mail is one of the most popular activities on the Internet. The widespread use of this technology, however, makes it a primary way for computer viruses to spread. Because viruses and other security threats are often contained in e-mail attachments, Microsoft Windows XP Service Pack 2 (SP2) helps protect your computer by blocking e-mail attachments that might be harmful.
In most cases, Windows XP SP2 will block files that have the potential to harm your computer if they come to you through e-mail or other communication programs. Windows will block these files if your program is running in a strong security mode. Most files that contain script or code that could run without your permission will be blocked. Some common examples of this file type are those with file names that end in .exe, .bat, and .js.
Blocking these files is very important to do, since directly opening files of this type poses a risk to your computer and personal data.
Is there any way I can open files that have been blocked?
If you are certain that you trust this file and want to open it, follow the instructions below.
Save the file onto your computer.
Click Start, click My Computer, and navigate to the file that you saved.
Right-click the file that you saved, and then click Properties.
Click Unblock near the bottom of the dialog box.
The reason it was added was because the slew of nasty worms/virus's that were released, they got alot of people, so Microsoft saw fit to themselves determine what files would be harmful and blocked them, they want to make sure that you know what your opening so they added an extra step to force people to understand what the certain file was and where it was from, alot of the blocking procedure is based on the type of file and signature, the type of file being the prominent factor, anything that could cause a danger to the system is blocked.
Although it specifically states email this also applies to files transferred thru messenger, aim and downloads. So anything thats downloaded that could be harmful is blocked. The second paragraph doesn't define communication programs, so it's open for interpretation.
It hasn't effected older files, so if they've been on your system awhile they won't be blocked, I keep my serial number's stored off my computer on floppies they haven't been blocked as of yet.
Can it be turned off.....no
can it be avoided, sure use a different browser, not IE
It's on by default when SP2 is installed
it only effects files that didn't come from your own computer, so anything you generate on your system and use on your system is deemed safe, try sending it to someone else and it will be blocked if it is deemed dangerous.
and here's a fix for outlook:
I don't think it will solve the problem for anything bout outlook tho.
The thing that confuses everyone is simple they click the file unzip it and a text file or harmless file is unzipped, for instance vso sends a zipped email it contains the reg entry and the readme for installation, when it's unzipped only the read me is unzipped not the reg file.