Quickly compress / uncompress all pictures and attachments of emails in outlook

Author: Siluvia Last Modified: 2025-04-03

Kutools for Outlook

While sending a message with large attachments embedded, you would like to compress these attachments in order to make sending faster. And for the emails with attachments you have received, compressing them can release your folder space and make your Outlook run smoothly. With the" Compress All" and "Uncompress All" utilities of "Kutools for Outlook", you can quickly compress and uncompress all attachments in one or multiple emails. Besides that, the" Auto Compress" utility allows you to auto compress all received attachments or compress received attachments automatically by specified rules.

Compress all attachments of one or multiple selected emails

Compress attachments of one or multiple selected emails by conditions

Uncompress all attachments of one or multiple selected emails

Auto compress all received attachments in Outlook

Auto compress received attachments by specified rules

Compress All Attachments Of One Or Multiple selected Emails

Please do as follows to compress all attachments of one or multiple selected emails in Outlook.

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1. Open an email folder and select one or multiple emails with attachments you want to compress at once.

2. Click "Kutools Plus" > "Attachment Tools" > "Compress All." See screenshot:

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3. In the "Compress Settings" dialog box, check the "Compress all attachments" option and then click the "OK" button.

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Tips: If you don’t want to display this "Compress Settings" dialog again in current Outlook session, please check the" Don’t show this Compress Settings dialog again in current Outlook session" box. But if you reopen Outlook, the Compress Settings dialog will be displayed again when applying the feature.

3. Then a "Compress All" dialog box pops up, click the "Yes" button.

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Then all attachments (including picture attachments) in the selected emails are compressed immediately.

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Compress attachments of one or multiple selected emails by conditions

Sometimes, you only want to compress some specific attachments in selected emails rather than compressing all of them. The Compress All attachments feature also provides some conditions for you. Please do as follows.

1. Select an email or multiple emails containing attachments you will compress some of them.

2. Click "Kutools Plus" > "Attachment Tools" > "Compress All".

3. In the "Compress Settings" dialog box, supposing you only want to compress the type of .xlsx attachments which the size is more than 600, please configure as follows.

Check the "Compress attachments that match the following condition" option;
Check the "Attachment type" box and enter the file extension (.xlsx) into the text box (For multiple extensions, please separate them with semicolon);
Check the "Attachment size" box, choose "More than" from the drop down list, and then type the attachment size (600) in the text box;
Click the "OK" button.

Note: Please specify the conditions based on your needs.

4. Then a "Compress All" dialog box pops up to remind you whether to compress the attachments, click the "Yes" button.

5. A "Kutools for Outlook" dialog box pops up to tell you how many attachments have been compressed; click "OK" to close it.

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Then only the attachments that meet the conditions have been compressed in selected emails.

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Uncompress All Attachments Of One Or Multiple selected Emails

This section is going to introduce the "Uncompress All" attachments of "Kutools for Outlook" to help you quickly uncompress attachments in one or multiple selected emails.

1. Select one or multiple emails which containing the compressed attachments you will uncompress.

2. Click "Kutools Plus" > "Attachment Tools" > "Uncompress All." See screenshot:

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3. In the popping up "Uncompress All" dialog box, click the "Yes" button.

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Then all compressed attachments (including picture attachments) in selected emails are uncompressed.

Note: This utility is only applied to the attachments which are compressed by our "Compress All" feature.

Demo: Compress and uncompress all attachments in multiple emails

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Auto compress all received attachments in Outlook

If you want to automatically compress all received attachments, the "Auto Compress" utility of "Kutools for Outlook" is your best choice.

1. Firstly, please turn on the feature by clicking "Kutools" > "Auto Compress" > "Enable."

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2. In the popping up "Kutools for Outlook" dialog box, click the "OK" button. Now the "Auto Compress" feature is turned on.

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3. And then click "Auto Compress" > "Auto Compress Manager" under the "Kutools" tab.

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4. In the "Auto compress attachments" dialog box, please configure as follows.

Check the "Auto compress all received attachments" option;
In the "The file extension after compressing" section, choose one option as you need.
Click the "OK" button to finish the setting. See screenshot:

From now on, when receiving emails with attachments in Outlook, all attachments (including picture attachments) will be compressed automatically.

Auto compress received attachments by specified rules

When receiving emails, if you only want to automatically compress all .xlsx extension attachments with the size of more than 600 kilobytes, you can create a rule with specific conditions to achieve it with the "Auto Compress" utility. Please do as follows.

1. Click "Kutools" > "Auto Compress" > "Enable." In the popping up "Kutools for Outlook" dialog box, click the "OK" button. Then the "Auto Compress" feature is turned on.

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2. And then click "Auto Compress" > "Auto Compress Manager" under the "Kutools" tab.

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3. In the "Auto compress attachments" dialog box, you need to:

Check the "Auto compress received attachments by rules" option;
Click the "New" button.

4. In the "Auto compression rule" dialog box, please configure as follows.

Enter the rule name in the "Rule name" text box;
In the "Filter" conditions, specify the conditions you need (in this case, only enable the "Attachment type" and "Attachment Size" conditions as follows);

1) Check the "Attachment type" box, enter the file extension “.xlsx” in the text box;
2) Check the "Attachment Size" box, choose "More than" from the drop-down menu, and then enter "600" in the text box.

In the "Compressed extension" section, choose an option as you need;
Click the "OK" button.

5. When it returns to the "Auto compress attachments" dialog box, you can see the created rule already checked and the details of the rule shown in the "rule description" box. Please click "OK" to finish the settings.

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From now on, when emails arrive in Outlook, the .xlsx attachments with a size of more than 600KB will be automatically compressed.

Notes:

1. In the "Auto compress attachments" dialog box, you can edit or delete a created rule using the "Edit" or "Delete" buttons.

2. To batch delete rules listed in the "Auto Compress Attachments" dialog, first select them using the "Shift" and/or "Ctrl" keys, right-click the selection to bring up the menu shown below, and then click Delete.

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3. If the rule description is too long to display fully in one line, you can check the "Display the rule description inline wrap" box.

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4. To compress or uncompress a single attachment or multiple selected attachments in an email, select the attachment(s) in the Reading Pane, then go to the "Attachment Tools" tab, click the "Kutools" tab, and then click "Compress" or "Uncompress".

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5. When compressing attachments manually or automatically, picture attachments are processed by default. If you don’t want to process picture attachments, click "Kutools" > "Options" (arrow in the lower right corner of the "Attachments" group). In the "Attachment options" dialog box, uncheck the "Process picture attachment" option under the "General" tab, then click "OK".

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6. To automatically compress attachments before sending emails, open the "Attachment options" dialog via "Kutools" > "Options", then check "Automatically compress attachments before sending emails" under the "Compress" tab.