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E-mail Blocked Filename Extensions

Overview   |  Blocked Extensions  |   Requesting Additions or Deletions

Overview

A variety of file types are dangerous for transmission via e-mail because they are executable programs and/or have the potential to damage the recipient's machine if opened. These file types are commonly identified by their filename extensions. Files with these extensions will be blocked by our e-mail servers.

Of course, the e-mail sender can simply change the filename to something with a different extension to avoid being blocked. But, by changing the extension, the recipient's machine will not know how to open or run the file, which protects it from inadvertent execution of a potentiall harmful file. The recipient can change the extension back to the original value to open or run the file. The recipient should only do so for files that they trust to be virus free.

 

Blocked Extensions

Extension	Description
ade	Microsoft Access Project Extension
adp	Microsoft Access Project
app	Mac OS X executable application program
asf	Microsoft Advanced Streaming Format file
asx	Windows Media Audio / Video
bas	Microsoft Visual Basic class module
bat	Batch file
chm	Compiled HTML Help file
cmd	Microsoft Windows NT Command script
com	Microsoft MS-DOS program
cpl	Control Panel extension
crt	Security certificate
dbx	Microsoft Visual Foxpro Table
dll	Dynamic link library
exe	Program
gadget	Microsoft Windows Desktop Gadget file
hlp	Windows Help file
hta	HTML Application
hto	Setup Information
inf	Setup Information File
ins	Internet Communications Settings
isp	Internet Communications Settings
jar	Java program
js	JScript file
jse	JScript Encoded Script file
lib	Static link library
lnk	Shortcut
mda	Microsoft Access Add-in
mdb	Microsoft Access program
mde	Microsoft Access MDE database
mdz	Microsoft Access Wizard template
msc	Microsoft Common Console document
msi	Microsoft Windows Installer package
msp	Microsoft Windows Installer patch
mst	Microsoft Windows Installer transform; Visual Test source file
nch	Outpost Express Folder file
ocx	Microsoft object linking and embedding files
ops	Office XP settings
pcd	Photo CD image; Microsoft Visual compiled script
pif	Shortcut to MS-DOS program
pl	Perl Script
prf	Microsoft Outlook profile settings
py	Python Script
pyc	Python Compiled Script
pyo	Python Compiled Optimized Script
reg	Windows Registry file
scf	Windows Explorer command
scr	Screen saver
sct	Windows Script Component
sh	Shell script
shb	Shell Scrap object
shs	Shell Scrap object
sys	Microsoft operating system or device driver files
url	Uniform Resource Locator (Internet shortcut)
vb	VBScript file
vbe	VBScript Encoded script file
vbs	VBScript file
wmd	Windows Media Download package
wms	Windows Media Player Skin
wmz	Compressed Windows Media Player Skin
ws	Windows Script Component
wsc	Windows Script Component
wsf	Windows Script file
wsh	Windows Script Host Settings file

 

Requesting Additions or Deletions

To request that a filename extension be added or removed from the list of blocked extensions, please submit the extension name, description and reason for the change to the scc-email Yahoo group.

 

If you have E-mail Networking Information that you would like to have included here,
please contact the Webmaster, Phil Henderson