Sending email with accented characters

[pagv]

I'm trying to send an e-mail message from a VB variable, which
contains accented characters, like this:

dim str = "Acentuação" ' this string contains a c-cedilla and an
a-tilde
dim objMail As New MailMessage()
objMail.Body = str
[...] 'all other objMail property settings follow

The message is delivered OK, but all the accented characters appear as
2 characters. The str string above would show like 'Acentuação'.

I know this is due to all VB variables being unicode and text e-mail
not supporting it, but I'd already tried all possible encodings and it
didn't help.

I'd greatly appreciate any help.