If you're transferring your email messages from another provider to Hostinger, follow the guide based on your situation:
Migrate emails to Hostinger Email
Import emails to Titan Email
If you're moving between different providers, not to Hostinger, the Imapsync tool can assist you.
On the IMAP source mailbox to the left, add your full email address, password, and IMAP server name of the email that you want to transfer from.
For the IMAP destination mailbox on the right, provide your destination email details.
Next, click on the Sync or resync button:
The synchronization might take a while. Keep the page open until the process is finished to prevent any disruptions.
NOTE
The IMAP Sync is limted to transfer up to 3GB. If your email account exceeds this limit, you can consider an alternative approach: create an email backup using an email client and then import it into your new email account