If your Outlook started to block attachments recently due to the long filename or filename containing extra dot or characters that are not letters or numbers, blame on the Outlook updates released in June 2017.
Outlook blocked access to the following potentially unsafe attachments
The attachment blocked in the above screenshot is because it has an extra “.” (dot) at the end of the filename before the file extension.
Which updates are responsible?
Here is the list of Outlook updates that will block certain attachments once installed:
- Outlook 2007 Service Pack 3 – KB3191898
- Outlook 2010 Service Pack 2 – KB3203467
- Outlook 2013 Service Pack 1 – KB3191898
- Outlook 2016 – KB3191932
These are the security updates that fix the following vulnerabilities in Outlook that could allow remote code execution if a user opens a specially crafted Office file.
- Microsoft Common Vulnerabilities and Exposures CVE-2017-8506
- Microsoft Common Vulnerabilities and Exposures CVE-2017-8507, and
- Microsoft Common Vulnerabilities and Exposures CVE-2017-8508.
Because these are the security updates, it’s not recommended bypassing it or uninstalling it from your Windows. Here are a few workarounds that you can use to retrieve temporarily blocked attachments.
Through Outlook Web Access
These updates don’t affect OWA access. So if you have access to Outlook Web Access for your email, you can open and read these blocked attachments. You can download them and rename them properly, and then forward them over to yourself or next person in your workflow.
Again, these updates have no effects on iOS and Android devices. So you can open emails on your smartphone and read the blocked attachments there.
Uninstall these updates
If you have just got too many attachments being blocked this way, it’s probably a good idea to uninstall these updates for the time being. However, massively uninstalling this update through Group Policy or script in a large network is still not recommended.
Open Control Panel, go to Programs > View installed updates, and find the update listed above. Then click Uninstall button.
You will need to restart your computer after uninstalling the update.
That’s it for now. Hope it helped.
/Update on June 27, 2017/
The fix for this issue has been released for Outlook 2010 and Outlook 2013 on June 27, 2017:
THANK YOU VERY MUCH
This was very helpful!!!!!
Thanks a lot, this was driving me crazy trying to figure out what the attachments had in common that was causing them to be blocked.
you are the best
its very help full
I have exactly the same problem as described, except when I uninstall the relevant update KB…1898 still shows in the installed updates section and this is after a restart which suggests the update is not being uninstalled despite the system telling me it has been. Any ideas?
Does anyone know if Office 365 Outlook 2016 does the Security Updates in the background, therefore making it impossible for me to uninstall? I ask because I am having this issue but do not see any of the Security Updates mentioned in this article.
I don’t think so. I believe the security updates are still part of the Windows Updates. The updates from Office 365 are the feature updates most of the time.