Outlook automatically converts all messages to Plain Text

What do you have for Tools, Options, Email Formats?

This might be it:

https://www.experts-exchange.com/questions/22736797/Read-all-standard-mail-in-plain-text-checkbox-is-greyed-out-urgent-500-points.html

To summarize it:
You might have a setting in your current Active Directory (AD) profile that's disabling those options within Outlook 2003. To enable these options in the AD profile go to: Microsoft Office Outlook 2003/Tools | Options.../Preferences/E-mail options. I would read the full post in the link though, just in case I missed something.

https://www.experts-exchange.com/questions/22736797/Read-all-standard-mail-in-plain-text-checkbox-is-greyed-out-urgent-500-points.html

Ok, I'm having a bit of a problem.  The post made by war1 on the question hyperlinked to by mystics and mi doesn't work.  frmcache.dat doesn't exist, and neither does outprnt.  I typed in regsvr32 OLE32.DLL and I get a message that says DllRegisterServer in XXX.DLL failed.  Return code was:  0x80004005.  I disabled all of the Add-Ins, and still no change.  I did the Detect and Repair option, and still no change.

The OP from that post doesn't make any sense to me.  He said that the "Read all mail in Plain Text" line was grayed out, just like mine is, and then, when he said he found the solution, the path that he put in goes to the "Read all mail in plain text" option.

Maybe I'm not understanding something.

Any ideas?

When he refers to the "Read all mail in Plain Text" setting in the final fix, I believe he is referring to the setting within Active Directory on the Exchange Server; not the setting within Outlook. AD allows policies to be setup with custom program restrictions for each user or group.

I believe this setting in Active Directory governs whether or not the checkbox is available to the user within Outlook itself. I am not sure how the restrictions for your user account got changed, but that sounds like what happened. I am not an exchange guru so if someone can explain this better, more power to them :)

The above assumes you have access to the Exchange Server. If this is just Outlook set up on a local machine, you may want to check the registry key for this setting in outlook. You can find it under:

HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail

There should be a REG_DWORD with a value of '0'. If this key is missing or the value is set to '1', that could be the problem. If you make any changes to your registry, please make a backup first!

Hope this helps!

EDIT:
"There should be a REG_DWORD, called 'ReadAsPlain', with a value of '0'. If this key is missing or the value is set to '1', that could be the problem. If you make any changes to your registry, please make a backup first!"

Um, I'm always scared of making registry changes, so i just want to clarify before I do anything crazy to it.  I have two items in my registry in the folder you specified.  One is a Reg_SZ called (Default) with no value set, and the other is a REG_DWORD called EnableLogging with the value set to 0x00000000(0).  So, since neither one of these is called ReadAsPlain, I should create it, and set the value to 0x00000000(0).  That correct?

Sorry if this looks like an exact repeat of what you just said, I just want to make sure I have it right before I do it.

Just to clarify myself a bit better:

Under "HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail" I see the blank Reg_SZ, this is fine, you can leave it. However, I do not see one called "EnableLogging", this may not be a problem as people's settings differ from computer to comptuer, but make sure that you have navigated to this exact location:
"HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail"
NOT
"HKEY_USERS\Software\Microsoft\Office\11.0\Outlook\Options\Mail"
or something else similar

There is a difference.

If you are at all concerned, I would make either a backup of the registry or simply set a restore point  (Start->All Programs->Accessories->System Tools->System Restore->"Create Restore Point") before you make any changes. After you have done this, re-open regedit and go to the previously mentioned location:

"HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail"
(if you get here and still see the "EnableLogging", don't worry about it.)

Now, right-click in the empty white space on the right-hand pane and select 'New->DWORD Value'.
Enter "ReadAsPlain" for the name and press 'Enter'.
Press 'Enter' again to open the edit window and enter '0' for the value data.
Click "Ok", then close regedit and restart the computer.
After windows reboots, open Outlook and see if the checkbox is still greyed out or if it fixed it.

Let me know what happens. :)

Ok, I created a new DWORD Value, named it ReadAsPlain, and set the value to '0'.  There was no change to the checkbox.  It is still grayed out.  Any other suggestions?

There is no Office in Policies.  It goes HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft. There isn't an Office folder in the Microsoft Folder.  The only folders in there are Conferencing, Cryptography, Internet Explorer, Netlogon, System, SystemCertificates, W32Time, Windows, and Windows NT.

As far as the Active Directory, I have to be honest, I don't know what that is.  I can access our exchange server.  When I type in the IP address for it in Internet Explorer, it comes up like a networked drive, with 2 shared folders in it.  One is called 'Address' and the other is the name of the exchange server with a '.log' at the end of it.  I can't access that one.

I'm checking right now with some of the computer guys here, to find out if they know how to access the Active Directory.  I guess I'll let you know once I find out.

Thanks alot,
~Skid