Blocking file attachments that are most commonly used to spread viruses will help protect University computer systems and data.

ITS uses the following list of attachments that will automatically be blocked due to their potential risk:


ace ade adp ani app asp aspx asx
bas bat cer chm cmd cnt com cpl
crt csh der docm exe fxp gadget hlp
hpj hta htc inf ins isp its jar
js jse ksh lnk mad maf mag mam
maq mar mas mat mau mav maw mda
mdb mde mdt mdw mdz mht mhtml msc
msh msh1 msh1xml msh2 msh2xml mshxml msi msp
mst ops osd pcd pif plg prf prg
ps1 ps1xml ps2 ps2xml psc1 psc2 pst reg
scf scr sct shb shs tmp url vb
vbe vbp vbs vsmacros vss vst vsw ws
wsc wsf wsh xml      



Newly added file extensions (per Microsoft)

py pyc pyo pyw pyz pyzw ps1 ps1.xml
ps2 ps2xml psc1 psc2 psd1 psdm1 cdxml pssc      
appref-ms udl wsb cer crt der jar jnlp
appcontent-ms settingcontent-ms cnt hpj website webpnp mcf printerexport
pl theme vbp xbap xll xnk msu diagcab



Messages containing these attachments are still delivered but the file attachment is removed. You will receive an error message from Postmaster with the subject of "Undeliverable message"

This message was created automatically by mail delivery software. Your email message was not delivered as is to the intended recipients because malware was detected in one or more attachments included with it. All attachments were deleted.

--- Additional Information ---:

Subject: attachment test


Time received: 6/22/2017 5:14:09 PM

Message ID:<>

Detections found:

testing.docm     docm


All messages with an attachment that is considered safe (or that has no attached file) will be delivered intact. Office productivity files (documents, spreadsheets, etc), text files, and other files that are not executable programs will be delivered as usual.  

If a *.zip file contains a file with an extension (such as .EXE), which is in the list of suspect attachments above, the entire zip file is removed. 

Encrypted/Password Protected Attachments

If a file attachment is encrypted, or if it is password protected, and therefore cannot be examined for malicious code, the entire message including the attachment will be delivered (Examples are encrypted .zip files, and password protected office productivity files.)  No warning is given to the recipient that the file has not been scanned.


Article number: 
Last updated: 
November 15, 2019