Outlook changes the mail format from Lotus Notes

[demarco]

I cannot read the same email format sent from Lotus Notes 7.0 users. When
they send Vietnamese email to me. I have to:
- Open the email
- Choose Other Action/Encoding/Vietname
- Then choose back to Unicode UTF-8
- Email display in Vietnamese
- Close the email, outlook request to save. Save. Back to Inbox
- In preview pane, or open the email again --> nothing changed, I still
cannot read in Vietnamese until perform the above procedure.
- Besides some emails sent to me were changed into Plain text format?

Please instruct me how to solve this to read email sent from L/N in it's own
form.

Thank you very much for your help.