Message List columns for custom headers
It's great that we can configure which items to show as columns in the message list.
This would be even better, if we had the option to configure any custom headers to be displayed as a column.
My personal use case for this: I'd love to see the content of
X-Spam-Score for each message to get an impression of how my mail provider's spam filter is keeping up with current events and if it would be wise to change the spam detection threshold.
For me it would be sufficient to simply display the text content of custom headers without any interpretation. One might think about adding support for different data types, which might have benefits when using custom headers for sorting.