The file contains a code pipe “|” to a custom command

id:content-code

This error indicates, that you are redirecting mails directly to programming scripts. This is not supported in the standard mailsetup and you will need to find another way to automatically process your incoming mails.

Error

Fatal Error: This configuration is not working with the standard mail system and we are not able to migrate it. You need to fix it or find a workaround using the uberspace mail commands.

Workaround for custom code scripts

The most common tools to workaround this could be fetchmail oder getmail which you can use to collect mails from a mailbox and then process them with your code. You could also configure your code to fetch the mails directly from the mailbox.

Workaround for mail filtering with |maildrop

If you used server-side mail filter scripts with |maildrop you should be able to replace them with Sieve filter rules. Just have a look to the filters & rules manual page.