Check the application's current dependency list and identify the runtime used by its mail-import process. A browser request, cron job and background worker may use different PHP executables. Keep a sample message that contains no confidential customer information for testing.

1. In Plesk, select the correct subscription and open PHP Selector from the available sidebar or additional tools. This guide applies to Linux subscriptions where the CloudLinux integration is installed. Windows Plesk uses its own PHP configuration.
2. Check the active PHP version and which websites the selector change will affect. Plesk also has a native PHP Settings page for each domain. A CloudLinux setting will not automatically override a different Plesk PHP handler. Confirm which handler serves the website first.
3. Open Extensions for the active PHP version and locate mailparse.
4. Enable it and save if required. Mailparse requires mbstring to be loaded before it, so confirm that dependency is enabled in the same runtime. Ask support to correct a package or load-order problem; the selector only offers extensions installed by the server administrator.
5. Run the application's dependency check and import a small test message with a harmless attachment. Verify the scheduled importer separately if it runs through cron.

Confirm that the application reports the extension available and correctly separates the message sender, subject, body and attachment. Check character encoding with a representative multilingual message if your helpdesk handles multiple languages.

If the browser reports success but cron still fails, compare the cron PHP path and loaded extensions. If an extension is unavailable for the selected version, ask support for the supported combination. Do not paste real customer messages or mailbox credentials into a public diagnostic page.

• Changing PHP versions, extensions and application limits
• Creating and monitoring cron jobs and scheduled tasks
• Creating a business mailbox and connecting your email apps
• Enabling the GD image extension with CloudLinux in Plesk
• Enabling ionCube Loader with CloudLinux in Plesk

• CloudLinux: PHP Selector for users
• CloudLinux: PHP Selector and control panel integration
• PHP: Mailparse