1. In the mail view, create a new email with clicking Home > New Email.

2. Click the Hyperlink button on the Insert tab. (Note: The Hyperlink button won’t be valid until you put cursor in the message body.)

3. In the Insert Hyperlink dialog box, click the Browse button  behind the Link in box.

4. In the Link to File dialog box, (1) Open the share folder that both you and massage recipients can open; (2) Click to highlight the file you will send as hyperlink in the opened shared folder; (3) Click the OK button.
Note: If the attached file is not saved in the shared folder, copy and paste the attached file into the share folder before this step.

Now you will get back to the message window, and the attachment is added as a hyperlink. See screen shot below:

5. Compose the email message, and then click the Send button to send the message.

Sometimes, you may want to replace the attachments with hyperlinks in received emails for the sake of reducing Outlook size, or other purpose in Outlook. In this condition, you can apply Kutools for Outlook’s Detach All (Attachments) feature.

1. In the Mail view, open the mail folder and select multiple emails whose attachments you will replace with hyperlinks. See screenshot below:
Note: Holding the Ctrl key, you can select multiple nonadjacent emails by clicking emails one by one.

2. Click Kutools > Attachment Tools > Detach All. 

3. In the opening Browse For Folder dialog box, please specify the destination folder you will place the attachments in, and click the Ok button. See screenshot below:

And now all attachments in all selected emails are replaced with hyperlinks as below screenshot shown. And the attached file will be opened when clicking on the corresponding hyperlink.

For automatically replacing all attachments with hyperlinks for all new incoming emails in Outlook, you can configure Kutools for Outlook’s Options to get it done.

1. Click launch icon at the bottom-right corner of the Attachments group on the  Kutools tab.

2. Now in the popping up Attachment Options dialog box, please go to the Detach & Save tab, check the Auto detach all receiving attachments option, specify the destination folder in the Save Folder box, and click the OK button. See screenshot:

From now all, all attachments in the incoming emails will be replaced with hyperlinks automatically.