If you are looking to save IMAP emails locally then here is the best article for your backup IMAP email. This article will provide effective manual methods to accomplish the process. 

Here are the following steps to download IMAP Email Locally.

• Launch the Outlook application and navigate to the File tab.
• In the Open & Export tab, click on the Import/Export icon.
• The import and Export Wizard will appear on the screen in which the Export to a File option and click on the Next button. 
• Now, choose the Outlook Data File (.pst) and click on the Next button
• Here select the IMAP folder you want to backup and click on the Next button.
• After that, choose the location by clicking on the Browse button and hit the Finish button.

However, the manual solution is a too lengthy process and time-consuming. So, additionally, they will also offer an advanced solution IMAP Mail Backup Tool. The software is the most secure tool to backup IMAP emails locally. Moreover, you can save the IMAP mailbox to multiple formats without affecting the data. You can try the trial versions of the software.