There is not a way to opt out of attachment blocking.  The policy is in place to protect the campus from potential threats and blocking file attachments that are most commonly used to spread viruses will help protect University computer systems and data. 

Messages containing these attachments will not be delivered.  You will receive an error message from Postmaster with the subject similar to "Undeliverable: message subject"

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 an Office file contains a macro or other malicious file type and has an extension of .docm, it will be blocked and won't be delivered.

If a *.zip file contains a file with an extension (such as .EXE), which is in the list of suspect attachments above, the message is not delivered.

 

Additional information on the Anti-Spam Service: Anti-Spam Service Information

List of Blocked File Types

The following is a list of blocked file types:

aceadeadpaniapkapp
applicationappref-msappxarjaspaspx
asxbasbatbgicabcer
chmcmdcntcomcplcrt
cshdebderdexdiagcabdll
docmelfexefxpgadgetgrp
hlphpjhtahtcimginf
insisoispitsjarjnlp
jsjsekextkshlhalib
librarylnklzhmachomadmaf
magmammaqmarmasmat
maumavmawmcfmdamdb
mdemdtmdwmdzmhtmhtml
mshmshmsh1msh1xmlmsh2msh2xml
mshxmlmsimsixmspmstmsu
opsosdpcdpifplplg
ppappamprfprinterexportprgps
ps1ps1xmlps2ps2xmlpsc1psc2
psd1psdm1pstpypycpyo
pywpyzpyzwregrevscf
scrsctshbshssystheme
tmpuifurlvbvbevbp
vbsvhdvhdxvsmacrosvssvst
vswvxdwebpnpwebsitewswsc
wsfwshxbapxllxmlxnk
xzz    

 

For the most current list of file types, see https://support.microsoft.com/en-us/office/blocked-attachments-in-outlook-434752e1-02d3-4e90-9124-8b81e49a8519
 

If a legitimate attachment (from a known sender or it was expected) is removed, can it be retrieved?

No, once removed, an attachment cannot be retrieved or restored.

Ask the sender to:

  1. Rename the attachment to docname.ext.rename.rename (where docname.ext is the original name of the attachment including the extension)
  2. Send the attachment again (with this new name) and a personal message to you.

When you receive this new message with the attachment, you will need to:

  1. Download the attachment.
  2. Scan it with your virus checker.
  3. Rename it. (Windows: right click on the file and select Rename. You need to delete the part of the name that says ".rename" or ".rename.rename".)

 

Options for Sharing Files
  • Rename the file so that it does not have a prohibited three-letter extension on its name, and then have the recipient rename the file back after they receive it. (For instance, rename "myprogram.exe" to "myprogram.xxx" and then attach and send it.) - See steps below for more information
  • Share the file using OneDrive through Microsoft 365 with your HawkId@uiowa.edu. 
  • Place the file on a shared drive, such as your department "L:" drive space, and send the person its location.
  • Place it on a web server and send the person a link to its location 
     

Ask the sender to:

  1. Rename the attachment to docname.ext.rename.rename (where docname.ext is the original name of the attachment including the extension)
  2. Send the attachment again (with this new name) and a personal message to you.

When you receive this new message with the attachment, you will need to:

  1. Download the attachment.
  2. Scan it with your virus checker.
  3. Rename it. (Windows: right click on the file and select Rename. You need to delete the part of the name that says ".rename" or ".rename.rename".)

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.

Best Practices for E-mail Attachments

Can certain file types be removed from the list of files to be removed?

No, since the list of file types are deemed potentially unsafe, we do not make exceptions.

Are Outgoing Messages with Attachments Blocked if on the Potentially Unsafe List

Yes, messages are scanned and blocked from sending if they contain potentially unsafe attachments. 

Sample Error Message
email delivery error with unsafe attachment
delivery error unsafe attachment

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6871