Hi,
First of all thank you for being such a good email program.
Secondly, thank you very much for implementing paid version of Thunderbird - Pro, Mail etc. As a business user I would like to see my favourite program growing and improving, but your business model doesn't allow that (donations are not business model). But now I'll be able to support you. Thank you.
I would like to suggest you adding few essential buttons to Card View. Here is a visualisation of m proposal:
1. Message area - these buttons are the most used and would allow to perform actions without even opening email - marking as spam, deleting, archiving emails.
2. Attachment area - here the same - performing actions on attachments without even locking at message body - immediately from message list
3. Tags area - tags made more visible, brought forward and put next to date and star. Again - to see essential information without accessing message content but only from card list view.
These suggestions came from my experience using Thunderbird and some other clients and I hope these would make reading and navigating more convenient.
Here is the image without red lines:
Thank you
Saulius