All of your partially-posted, unsent emails will remain in your Drafts folder until the day they are sent or deleted. In Apple Mail for iPhone, you can access all drafts of all accounts in a combined "All Drafts" folder from the main Mailboxes app – but only if you added them manually. However, there's an even better way to access all of your designs in Apple Mail on iOS. it's just not obvious.
This hidden trick works in iOS 13 as well as in all previous versions of iOS dating back to iOS 4 when the little-known link appeared for the first time. In the main list, press Mailboxes or any list or folder of a linked email account in the lower right corner of the new design icon, also known as the "Compose" button.
Modal The window with all your designs in all your accounts ̵
You can not access this shortcut through emails but you can access it from far more places than through the optional "All Drafts" folder on the main screen or the "Drafts" folder in the "Each account" area, wherever you see the "Compose" icon Recall all of your designs, whether you've started them on your iPhone or not.