I would like to highlight incoming messages from a specific sender and ideally receive a push notification. I would also like to increase the interval for checking/updating my email account linked to Thunderbird. How do I do this?

Thunderbird on Android doesn't have a feature to highlight or provide push notifications on an individual email basis. For the push notification, can I suggest a workaround that achieves your objective. Setup a server-side rule (via your webmail) that moves new emails from the sender to a dedicated folder. You can skip the above step if you're happy to receive push notifications from new emails hitting Inbox, or folder(s) of your choice. In the Thunderbird Android app, enable push notifications on your desired folder(s). # Open the account list # Tap account name # Tap manage folders (bottom of list) # Tap 3 dot menu # Tap refresh folder list # Tap folder name # Toggle "Enable Push" ON On Android 13 and later, grant Thunderbird the "alarm and reminders" permission, required for the push service. See the guide linked below. https://support.mozilla.org/en-US/kb/configure-push-email-thunderbird-android Android restricts apps with background sync. The interval can't be less that 15 minutes. The push service is recommended thereafter, and is the reason why push has a constatant forground notification. You can find "folder poll frequency" under settings > account > fetching mail You can raise any feature ideas you have on Mozilla connect, where they are opened to votes from the community. https://connect.mozilla.org/t5/ideas/idb-p/ideas/label-name/thunderbird%20android/tab/most-kudoed