We are aware of an issue in which the Mail app will crash in some cases when starting to compose a new message or reply, when PadKeys is the selected keyboard. Unfortunately this is due to a bug in Mail itself. We are trying to work around it, which we believe should be possible since not all third-party keyboards are crashing. When / if we find a solution we'll release a new version to the App Store right away.

For now unfortunately the only solution is to select another keyboard before entering Mail, and then switch to PadKeys once the message has opened. We apologize for this.