Microsoft Outlook does not support compressing attachments directly. But we can compress files firstly, and then sent the compressed files via Outlook. You can do as follows:

1. Find and select the files that you will compress and sent via Outlook, right click the files, and then select Send to > Compressed (zipped) folder. See screen shot below:

2. Now selected files are compressed to one file. Right click the compressed file, and then select the Send to > Mail recipient.

3. Then a new email is created with the compressed file as attachment automatically. Compose this email, and then send it.

Sometimes, you may want to compress attachments in received emails. Kutools for Outlook’s Compress All (Attachments) utility can help you batch compress all attachments in selected messages with just one click.

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1. Select the email messages whose attachments you will compress in the mail list, and click the Kutools > Compress All.

2. A Compress All dialog box pops up asking for your confirmation. Just click the Yes button.

Then you will see all attachments in each selected email messages are compressed immediately. See screen shot below:

Note: By default the Compress All (attachments) utility does not compress attachments of images. If need to compress attachments of images, please click here.

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Some Outlook users may think it time-consuming and boring to manually compress attachments in selected email messages. Actually, Kutools for Outlook supports automatically compressing attachments in incoming or outgoing messages.

Kutools for Outlook simplifies your daily email communication through Outlook by adding dozens of handy features. Read More      Free Download Now

1. Click the Kutools > Others > Options.

2. In the opening Attachment Options dialog box, go to the Compress tab, check the Auto compress all outing attachments option and Auto compress all receiving attachments option, and click the OK button.

From now on, if attachments exist in outgoing emails or coming emails, the attachments will be compressed automatically.

Note: By default the Kutools for Outlook’s Compress All Attachments utility ignore attachments of pictures. If you need to compress attachments of pictures, please click Kutools > Others > Options to open the Attachments Options dialog box, and then check the Handle image attachments option on the General tab. See screen shot below:

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