"Windows Live Hotmail has blocked some attachments ..." - how do I get around that?

Here's the message we're talking about:

Do not confuse this with similar messages that include links to "Show Content" - those are different. This message results when Windows Live Hotmail detects an attachment that has a specific file extension - the ".letters" at the end of the filename.

One list of blocked extensions includes:

• .ade (Microsoft Access Project Extension)
• .adp (Microsoft Access Project)
• .bas (Visual Basic Class Module)
• .bat (Batch File)
• .chm (Compiled HTML Help File)
• .cmd (Windows NT Command Script)
• .com (MS-DOS Application)
• .cpl (Control Panel Extension)
• .crt (Security Certificate)
• .exe (Application Executable)
• .hlp (Windows Help File)
• .hta (HTML Applications)
• .htm (HTML File)
• .html (HTML File)
• .inf (Setup Information File)
• .ins (Internet Communication Settings)
• .isp (Internet Communication Settings)
• .its (Internet Document Set)
• .js (JScript File)
• .jse (JScript Encoded Script File)
• .lnk (Shortcut)
• .mda (Microsoft Access Add-in)
• .mdb (Microsoft Access Application)
• .mde (Microsoft Access MDE Database)
• .mdt (Microsoft Access Add-in Data)
• .mdz (Access Wizard Template)
• .msc (Microsoft Common Console Document)
• .msi (Windows Installer Package)
• .msp (Windows Installer Patch)
• .mst (Visual Test Source File)
• .pcd (Photo CD Image)
• .pif (Shortcut to MS-DOS Program)
• .reg (Registration Entries)
• .scr (Screen Saver)
• .sct (Windows Script Component)
• .shb (Appfix Package)
• .shs (Shell Scrap Object)
• .url (Uniform Resource Locator)
• .vb (VBScript File)
• .vbe (VBScript Encoded Script File)
• .vbs (VBScript Script File)
• .vsd (Visio Drawing)
• .vss (Visio Stencil)
• .vst (Visio Template)
• .vsw (Visio Workspace File)
• .ws (Windows Script File)
• .wsc (Windows Script Component)
• .wsf (Windows Script File)
• .wsh (Windows Scripting Host Settings File)

(I won't claim this list is accurate or complete. As we know, things are always changing. By the time you read this additions and deletions could have occurred.)

As you can see in my example above, I emailed myself "du.exe" which is a ".exe" type, which is on the blocked list.

Why are all those file types blocked?

Because they're "executable". They are, fundamentally, computer programs or can be treated as computer programs.

And as computer programs, they can carry malware.

Hotmail is protecting you by preventing your accidentally downloading and running any file type that could carry malware.

And as far as I have been able to determine, there is no way to actually tell Hotmail you know what you're doing and to let you download the attachment anyway.

The Workaround

The workaround that you'll hear from almost every support person, and the easiest workaround that you'll hear from me is to have the person sending you the file resend it, with either of two changes:

• Have the person rename the file before attaching it. In my example I'd rename "du.exe" to "du.foo" before attaching it. Make sure to use an extension that is not on the blocked list. Then you should be able to download the attachment, and rename it back to it's original name prior to using it. Again, in my example after downloading "du.foo" I'd rename it "du.exe" and have the intended file.

• Have the person zip the file before attaching it. Not only will this typically make the file being emailed somewhat smaller, you'll note that ".zip" is not on the blocked list. You can then download the zipped file, and unzip it with a program like WinZip, 7-Zip or Windows Explorer itself.

The down side to both of those workarounds is that the file must be resent.

A Workaround That Works

An alternative that I've verified works is to configure a POP3 email program such as Thunderbird to download your Hotmail messages. The messages - and their attachments - will be downloaded and you can access the attachments according to the security settings of that email program.

This is more work; you'll need to potentially download and configure an email program to do it.

But it works.