Please add Rules to Thunderbird mobile and sync them to Thunderbird desktop. The QR approach to syncing accounts and settings between Thunderbird desktop and Thunderbird mobile is really nice. Adding Rules as an option to the QR checkboxes would be a great way to allow syncing Rules on demand between devices.
Rules are a really powerful way to manage email using Thunderbird desktop. K-9 email was a good email app -- good enough to merit Mozilla's attention, but its lack of ability to use Rules was one of its few weaknesses. Now that K-9 has become a core part of the new Thunderbird mobile app, that weakness should be corrected as soon as possible. Lacking the ability to set and sync rules between Thunderbird desktop and Thunderbird mobile makes things difficult for the mobile user.
For instance, rules can be set on Thunderbird desktop to mark email for deletion, move email to the Deleted folder, or delete email entirely. Rules can also be set to mark and tag email for better filtering, grouping, and sorting. Lacking those rules, Thunderbird mobile has only a search filter to aid the user in reducing the amount of email that is irrelevant to current session needs or preferences.
I'm certainly not telling you something you don't already know, but I hope you will seriously consider my feature request. I suspect a lot of Thunderbird mobile users will appreciate this improvement. I know I will.
Thanks for the work you do, and have a great day.