OU E-mail Attachment Policies


Due to an increase in malicious attachments, OU IT has restricted various attachment types that may contain macros and executable files. Executable files (files ending in .exe) can contain harmful code that may include malware or a virus. Please see this Microsoft support article for more information. To help prevent malicious attacks, the following file types have been restricted from email attachments:

Blocked attachment file types

*.ade *.ins *.ppsm *.vbe
*.adp *.isp *.pptm *.vbs
*.app *.js *.prf *.wsc
*.asx *.jse *.prg *.wsf
*.bas *.ksh *.ps1 *.wsh
*.bat *.lnk *.ps11 *.xlam
*.chm *.mda *.ps11xml *.xlsm
*.cmd *.mdb *.ps1xml *.xltm
*.com *.mde *.ps2 *.xnk
*.cpl *.mdt *.ps2xml  
*.crt *.mdw *.psc1  
*.csh *.mdz *.psc2  
*.dll *.msc *.reg  
*.docm *.msi *.scf  
*.dotm *.msp *.scr  
*.exe *.mst *.sct  
*.fxp *.ops *.shb  
*.hlp *.pcd *.shs  
*.hta *.pif *.url  
*.inf *.potm *.vb  

Please see the alternative methods below for sending attachments.

Attachment Alternatives

The University of Oklahoma Microsoft 365 e-mail system allows users to attach files to outgoing messages. Currently there is a 35 Mb size limit for file attachments on OU e-mail.

Hosting your file on an OU maintained site to supported application

The University offers services for hosting your larger files:
  • OneDrive for Business – OU Microsoft 365 users can share files through OneDrive with other indivduals. After logging in to https://office.com, a user can select OneDrive. After uploading your file, one can select the file and then hit the Share option. Enter the e-mail address of the user with whom you wish to share.
  • Dropbox for Business – Dropbox for Business allows teams and organization to securely share files. Just create a folder, share it, and start collaborating instantly. University Departments may purchase Dropbox for Business licenses, available to faculty and staff. For more information about Dropbox for Business, please visit OU IT’s Service Catalog.

Hosting your file on a non-OU site

Many third party sites offer hosting for large file sizes. Note that OU cannot ensure security of your confidential documentation if it is stored on a third party site. Please also ensure you are following any University, State or Federal policies for protection of personal information.

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Article ID: 89
Thu 9/3/20 12:10 PM
Tue 6/6/23 11:52 AM