I think it would be much appreciated to disable the Send button when creating new e-mails until the attachments are being uploaded.
Currently if the added attachment is still being uploaded and the users hits the Send button the e-mail gets sent without the attachemnt, the user has to create another reply to send the attachment.
I would reccomend disabling the option to click the Send button when the attachemnt is currently being uploaded or to wait for the Send button action until uploads are completed.
