You can use Opera Mail Backup Tool for Mac and takes backup of your Opera Mail without any data loss on mac with ease.

https://www.arysontechnologies.com/demo-version/Aryson-Opera-Mail-Backup-Tool_mac.dmg

If you are working on Linux operating system and have a need to take a backup of Opera Mail account then use Opera Mail Backup Tool for Linux.

https://www.arysontechnologies.com/opera-mail-backup/

@katito42 The software also offers a demo version that takes backup of Opera mail up to 50 email items. If it is suited for you, then you can use it free of cost.

Hi katito42, If you want to takes a backup of openra mail then you need to use Opera Mail Backup Tool, that taking a backup of email into various file format on your local machine. It is very useful software that takes Opera mail backup succesfully.

https://www.arysontechnologies.com/opera-mail-backup/