How to disable unwanted encoding in Outlook 2010/Exchange 2007?

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I'm running Outlook 2010 with a hosted Exchange 2007 server.

If I reply to a plain-text message encoded in UTF-8, the recipient receives the reply in content-transfer-encoding=base64. How do I disable that (ie, either leave the message in utf-8 or quoted-printable)? KB#278134 describes the problem but states " When Outlook uses Exchange to send the message, Outlook does not honor this registry setting." Indeed, it's not clear if that reg key is still present in O14.

Messing with File/Options/Advanced/International seems to have little or no effect.

Thanks in advance,

Peter Hurley


Hi Abdias,

When I reply using OWA light to messages with the following MIME header

Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit <or> 8bit
the recipients (gmail & pop) get

Content-Type: text/plain; charset=" Windows-1252" Content-Transfer-Encoding: quoted-printable

This is ok.

When I use Outlook through Exchange 2007 , the recipients get

Content-Type: text/plain; charset=" utf-8" Content-Transfer-Encoding: base64

This is bad.

In Outlook, I have tried *every* permutation of " Automatically select encoding for outgoing messages" , " Preferred encoding for outgoing messages" , and the registry key (HKCU\Software\Microsoft\Office\14.0\Outlook\Options\Mail\InternetMailTextEncoding) mentioned in KB#278134 - stopping and starting Outlook each time. Regardless of these settings, my reply MIME header is always the same (as above).

When I use Outlook through Pop , the recipients get

Content-Type: text/plain; charset=" utf-8" Content-Transfer-Encoding: quoted-printable

because that regkey mentioned above is currently set to 1.


Maybe I should cross-post anyway?

Abdias Ruiz

Cross posting may help. I asked an Exchange Connectors engineer and they advised Exchange 2007 will send using Base64 encoding. It may be possible to change it for a single user by having them create an Outlook contact for the intended recipient(s) and double-clicking on the email address in the contact, and in Outlook Properties, setting the option to never use Rich Text format (" Send Plain Text only" ). A global option would be to configure the sending Exchange org to always send Plain Text to recipients of a specific, remote domain.

Abdias Ruiz [MSFT]
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