Outlook 2010 "Send Plain text only" not working for individual contacts

Question

We have a Outlook 2010/Exchange 2007 environment
If you go to Outlook Properties of a contact and change from "Let Outlook decide the best sending format" to "Send Plain text only", it is supposed to force Outlook to send a Plain text
email
to that contact. 
But it is still sending HTML.  This is happening with any contact I try this with.
While composing the email I can change it to Plain text manually and that works fine.
Not sure what gives...

Answer 1

Hi,
I recommend that you check the global remote domain setting if set to send plain text.
If not , the remote domain setting will override the change of the contact's properties when sending email out. 
More details refer to the following article:
http://technet.microsoft.com/en-us/library/bb232174(v=exchg.141).aspx
Remote domain settings   Remote domains define the settings for outgoing message transfers between the Exchange 2010 organization and domains outside the Active Directory forest. Even if you don't create remote domain entries
for specific domains, there's a predefined remote domain named Default that applies to all remote address spaces (*).
Hope this helps!
Thanks.
Niko Cheng
TechNet Community Support