EML Viewer

EML Viewer opens email files that are stored on your phone. It supports
three formats: .eml (standard email), .msg (Outlook), and winmail.dat
(Outlook attachment). You can open a file from the file picker, from
Downloads, from a cloud drive, or by tapping it in any other app.

Each email is shown the way it was sent. You can read the body, view
the original headers, see the attachments, and save them to your
device.

You can also compose a new email — write a subject, recipients, body,
and attachments — and save it as a .eml file. Forward the file in any
mail app to send it.