If you are using gmail, please notices the special login button (''Login with Google'').
If you are using another mail provider, please consult the webpage of your provider to find out the settings or to give third-party applications access to your account.
We recommand to use Thunderbird with Enigmail on other devices to access your confidential mails. The EFF provides tutorials on how to set up Thunderbird with Enigmail on Windows, MacOS or Linux. Afterwards you can put securly your secret key from your iPhone on into your mail box. You start this process in your ID view. When opening this mail on your other device you have to input a password and you are done.
You can transfer your secret key from a different device to Letterbox using iTunes. You open iTunes on your different device and copy the key into the Letterbox folder. On Letterbox you click on ''Your keys'' in the management folder. Than you click on ''+'' and follow the steps to import the keys.