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Blocked Attachments in NUSmail

In NUSmail, there exist two layers of attachment type restriction, one of which is the blocking of attachments by Microsoft Outlook as well as the attachments that are blocked for incoming emails from the Internet.

Attachments blocked by Microsoft Outlook

For security, Outlook is designed to prevent you from opening up directly any unsafe attachments.

There has been frequent virus attacks in the past that have affected millions of people. Outlook has been updated to protect people from files, such as .exe and .bat files, that are often used to run malicious scripts when opened. This makes file sharing less convenient for many people, but security must take precedence.

Commonly used file types such as .doc, .xls, and .ppt files, are not blocked.

To send any of the following files, you can rename the files to include a temporary file type that is not on the list of blocked file types. For example, you might rename MyFile.exe to MyFile.exe_EXTRA and then attach the file to the e-mail message. You can include instructions in the message to save the file with the correct name, for example, MyFile.exe, when the recipients save the file to their computers.

Alternatively, zip up the attachment before you attach them to your e-mail message. In your message, you can include instructions explaining how to extract the files from the package to make it easy for recipients to access the files.

The following file types are blocked and cannot be accessed via Outlook.

File extension File type
.ade Microsoft Access project extension
.adp Microsoft Access project
.app FoxPro generated application
.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
.csh Unix shell script
.exe Program
.fxp FoxPro file
.hlp Help file
.hta HTML program
.inf Setup Information
.ins Internet Naming Service
.isp Internet Communication settings
.js JScript file
.jse Jscript Encoded Script file
.ksh Unix shell script
.lnk Shortcut
.mda Microsoft Access add-in program
.mdb Microsoft Access database
.mde Microsoft Access MDE database
.mdt Microsoft Access add-in data
.mdw Microsoft Access workgroup information
.mdz Microsoft Access wizard program
.msc Microsoft Common Console Document
.msi Microsoft Windows Installer package
.msp Windows Installer patch
.mst Visual Test source files
.ops FoxPro file
.pcd Photo CD image or Microsoft Visual Test compiled script
.pif Shortcut to MS-DOS program
.prf Outlook profile information (msrating.dll)
.prg FoxPro program source file
.reg Registration entries
.scf Microsoft Windows Explorer command
.scr Screen saver
.sct Windows Script Component
.shb Shortcut into a document
.shs Shell Scrap Object
.url Internet shortcut
.vb VBScript file
.vbe VBScript Encoded Script file
.vbs VBScript file
.wsc Windows Script Component
.wsf Windows Script file
.wsh Windows Script Host Settings file
.xsl XML file that can contain script

Attachments that are blocked on incoming Internet mails

The following file types are blocked on all incoming mails from the Internet. They are not accessible even if they are plainly zipped. For such cases please advise the sender to password protect the zip files before sending it to you. Alternatively the sender may rename the file extension before sending it to you.

File extentions


Macros embedded in word processing application files such as Microsoft Word and Excel.

Note: E-mails with Macros-embedded attachments will be detected as containing the GenericMac8_X97M virus. If that happens, please request the sender to re-send the attachment within a password-protected zip file.