Hi Glen You previously asked the same question on ticket : https://support.mozilla.org/en-US/questions/1581219. Please use the same ticket when responding about the same question. What issue is stopping you using Thunderbird on your phone, Please describe so we can offer you some assistance. What is your concern about mail security? If your concern relates to a feature the app doesn't currently support, please feel free to raise any suggestions and ideas you have on Mozilla connect. These ideas can then be voted on by the community. https://connect.mozilla.org/t5/ideas/idb-p/ideas/label-name/thunderbird%20android/tab/most-kudoed