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How to quickly unblock unsafe attachment types in Outlook?

Author: Xiaoyang Last Modified: 2017-07-04

If you have received some emails with attachments whose extension is msi, exe, etc. in your Outlook, you will get a warning message “Outlook blocked access to the following potentially unsafe attachments” as following screenshot shown when you open the massage. Outlook will consider these types of attachments as unsafe information by default. But, how could you set these attachment types as safe files and easily view or download in Outlook?

doc unblock attachment 1

Unblock unsafe attachment types in Outlook with modifying the regedit

Unblock unsafe attachment types in Outlook with Kutools for Outlook

Change default attachment size, saving folder / add blocked attachment extensions in Outlook:

With Kutools for Outlook’s Attachment feature, you can increase the attachment size as your need, and change the default folder for saving attachments, at the same time, you can add some extensions that Outlook blocks.


1. Change attachment size to your need;

2. Add blocked attachment extensions;

3. Change deafult attachment saving folder.

Download Kutools for Outlook freely!

arrow blue right bubble Unblock unsafe attachment types in Outlook with modifying the regedit

Normally, you can add the attachment extensions into the regedit to allow these specific types of attachments to be safe. Please do as follows:

1. Make sure the Outlook is closed.

2. Then click the Start button of the computer, in the search box, please type regedit, see screenshot:

doc unblock attachment 2

3. And then press Enter key, in the popped out User Account Control dialog, click Yes button to go to the Registry Editor window, in the Registry Editor window, please locate the following key:

(1.) Outlook 2010:


(2.) Outlook 2013:


(3.) Outlook 2016:


4. After going to the Security step by step, then click Edit > New > String Value, see screenshot:

doc unblock attachment 3

5. And then rename the item you have created just as Level1Remove, see screenshot:

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6. Then double click the created value and enter the extensions including the “dot” that you want to open in Outlook. For example: .exe, see screenshot:

doc unblock attachment 5

Tips: If you want to enter other extensions, you need to separate them by a semicolon like this: .exe;.bat;.url;.msi.

7. Then click OK and close the Registry Editor, now, launch your Outlook, the attachments which contain these specific extensions aren’t blocked by Outlook anymore. See screenshot:

doc unblock attachment 6

Note: If you want to block those extensions again, you just need to go to delete the Level1Remove value you are created in the Registry Editor.

arrow blue right bubble Unblock unsafe attachment types in Outlook with Kutools for Outlook

If you are confused by the above method, here, I can talk about an easy way, with Kutools for Outlook’s Safe Attachment feature, you can quickly set the safe attachment extensions you need.

Kutools for Outlook : with more than 20 handy Outlook add-ins, free to try with no limitation in 45 days

After installing Kutools for Outlook, please do with following steps:(Download Kutools for Outlook Now! )

1. Open your Outlook, and click Kutools > Options, see screenshot:

doc unblock attachment 07

2. In the Options dialog box, click Others tab, and then enter the attachment extensions that you want to be unblocked into the Safe Attachment Extensitions text box, such as: .exe;.msi;.vbs, see screenshot:

doc unblock attachment 08

Tips: When you type the extensions, you should add the dot before the extensions, and use semicolon to separate the extensions if adding multiple extensions at the textbox.

3. Then click OK button, a warning message will pop out to remind you taking effect the changes, you must restart Outlook, see screenshot:

doc unblock attachment 09

4. Then click OK, and restart your Outlook to take the settings effect.

Please download Kutools for Outlook freely and try it now!

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Comments (11)
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This comment was minimized by the moderator on the site
There is a far simpler solution to this:
1. Save email to .msg file.
2. Use free app like 7-zip to extract it in a same way you would extract compressed (zip, rar, etc.) folder.
3. Go into extracted folder and look for __attach_version1.0_#00000000. If there are more attachments or there is any pictures within the emails, there will be more of these folders.
4. Within each attachment folder you can find the file name of attachment in __substg1.0_3001001F.
5. Once you located your desired file, rename __substg1.0_37010102 to the file name from __substg1.0_3001001F. Windows will ask you to confirm with warning that file might become unusable.
6. Confirm the file name. You will notice that the icon of the file has change to what you would expect it to be based on file extension. You can now open/run the file.

Completely free, no admin rights required and no chance of corrupting any registry settings.
This comment was minimized by the moderator on the site
Obrigado pela dica, funcionou perfeitamente!
This comment was minimized by the moderator on the site
Thanks guy! It's worked with Outlook 2016.
This comment was minimized by the moderator on the site
Does that unblock the already received email attachment or is for future inbox(i mean incoming after that modification)??
This comment was minimized by the moderator on the site
The above methods applied for both existing email attachments and future incoming emails. You can try it. Thank you!
This comment was minimized by the moderator on the site
Awesome! This just saved me a ton of time!
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