I have the exact same problem, OS is XPHE.

Here is some information posted by Peter Jamieson.  It may not be applicable
to your operating system and mail program, for which it might be better to
ask your question in the microsoft.public.windows.vista.mail newsgroup, to
which I have cross-posted this response.

First, make sure that the e-mail program you want to use is set up to be the
default e-mail program (e.g. via Internet Explorer|Tools|Internet
Options|Programs, and send at least one message using it.

Then Word needs some stuff in WIN.INI and/or in the Windows registry
before it will show you the E-mail option. I believe that for Word 2003 it
needs to be in the Windows registry, but that may depend also on the version
of Windows so it is probably better to put the information in both places.

For WIN.INI,
a. find the WIN.INI file in your Windows folder (typically c:\WINDOWS),
make a backup copy of it, and open it in Notepad.
b. ensure that the following text is in there, and add it if not

[Mail]
MAPI=1
CMCDLLNAME32=mapi32.dll
CMCDLLNAME=mapi.dll
CMC=1
MAPIX=1
MAPIXVER=1.0.0.1
OLEMessaging=1

You will need to close all copies of Word before this change has a chance of
taking effect. It is probably safest to restart Windows to be completely
sure.

If that isn't enough, you will need to edit the registry. Proceed with
caution!

c. In your Windows folder, locate and run regedit.exe. If you're on an
older version of Windows you might need to use regedt32.exe.

Look for a key called

HKEY_LOCAL_MACHINE\SOFTWARE\Mi­crosoft\Windows Messaging Subsystem

I would be surprised if it was not there in recent versions of Windows, but
if it is not, add it.

If it is there, I would expect to see
d. a subkey claled MSMapiApps
e. a number of "values" with the same names as are in the above list -
MAPI, MAPIX etc.
f. an additional value called InstallCmd

If you cannot see the (e) values, you need to add them. For each of the
values in the above list
g. right click "Windows Messaging Subsystem" and select New|String Value.
Note that although some of these items have numeric values, they should all
be entered as String Values.
h. enter the name, as above
i. double click on the name. A dialog box appears. Enter the value (e.g.
for the name CMCDLLNAME, enter mapi.dll) and click OK
j. You may also need to create the InstallCmd value, although I rather
doubt it. I am less sure about this and about what should go in there. On my
system, the value is:
rundll32 setupapi,InstallHinfSection MSMAIL 132 msmail.inf

When you have done them all, press F5. Then close all copies of Word and
restart it - or restart Windows, then restart Word and see if the e-mail
option has appeared.

Solved problem of greyed out send email by downloading from the Microsoft
website the 2007 Microsoft Office Add-in: Save as PDF or XPS. This added
these features and opened the greyed out Sending email.
Now my problem is that no one can open these .docx files unless they have
Office 2007 or downloaded the Microsoft converter for the 2007 programs!

I talked to microsoft last night and boy was I furious and livid.  I just
purchased a Sony VAIO and this problem occurred.  I have tried to correct the
problem on my own.  First of all I had to go through Customer Service in
order to get Technical Support and they wanted $59, as I explained to them
that I have just purchased this computer and totally frustrated because
sometime I work at home and need to email my product to work.  Yes, I can
save the file on within Vista to email but that should happen because
Microsoft is communicating with their own problems.  It was explained to me
that Microsoft Office Home and Student 2007 is missing to two files that
would eleviate our problems.  I explained that they need to supply us with a
patch.  They also gave me the alternative to by downloading the add-ins which
also didn't for me.  WE NEED A PATCH, NOT BAD CUSTOMER SERVICE FOR SOMETHING
THAT MICROSOFT DID NOT FORSEE.   I AM NOT PURCHASING OUTLOOK AS SUGGESTED
BECAUSE AS FAR AS MY HOME COMPUTER IS CONCERNED I'VE NEVER HAD THE PROBLEM
BEFORE.  I INSTRUCTED MICROSOFT NOT TO CLOSE MY TICKET UNTIL THE PROBLEM IS
RESOLVED.  I AM LIVID.

Ben did you ever get a response?  I recently upgraded to Vista Ultimate and
MS Office 2007 Home and Student edition and have the same problem.  Is there
a way to set up Word so we can send a ducument within Word 2007 using our MS
Mail?

Thanks,

Bill
bhlh@comcast.net

I e-mailed the tech support folks at Microsoft.  What follows is their
response.  I followed the directions and "Step 1" solved the problem for me
in under 60 seconds:

-------------------------------------------------------

After several meetings on the diagnosis of the issue, all of us agreed upon
the fact that this issue is a by-design feature of Windows Mail.

I'm afraid we are unable to use Word, OneNote, or Excel etc to send or
receive emails via Window Mail. Actually, I personally think what you would
like to implement is very reasonable and understand how frustrating it is
when you find that the product does not meet your needs. I'm indeed sorry for
the inconvenience that this by-design feature of our products has caused you.
I will forward your suggestion to our development team so that they may
improve this in the future.

However, as my personal suggestion, I'd like to give a workaround as below.
Please try it and see whether it will meet your need. Thanks for your time
and efforts.

Step 1: Import registry

============================

1. Quit your Office programs, please click on the following link to download
the Messaging_registry.reg file to your desktop.

http://officetoolsdown.googlepages.com/Messaging_registry.reg

2. Double click on this Messaging_registry.Reg file to import the registry.
When you are asked whether you want to import the registry, click Yes.

3. Start Office programs like Word/Excel to check whether the E-mail icon is
useable.

If the E-mail icon is still shadowed, I would recommend you to perform a
manual check of the registry settings.

Step 2: Manually verify the registry settings

============================

Warning: If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system. Microsoft
cannot guarantee that you can solve problems that result from using Registry
Editor incorrectly. Use Registry Editor at your own risk.

1. Close all your open programs in Microsoft Windows.

2. Click Start and then click Run.

3. In the Open box, type “regedit” (without quotations), and then click OK.

4. Locate and then click the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
Messaging Subsystem registry key.

5. You should have the following registry values listed in the Windows
Messaging Subsystem key:

Name
Type
Data

MAPI
REG_SZ
1

CMC
REG_SZ
1

CMCDLLNAME
REG_SZ
Mapi.dll

CMCDLLNAME32
REG_SZ
Mapi32.dll

MAPIX
REG_SZ
1

MAPIXVER
REG_SZ
1.0.0.1

OLEMessaging
REG_SZ
1

6. If any one of the registry values are missing in the Windows Messaging
Subsystem key of the registry, follow these steps to add the values:

a. With the Windows Messaging Subsystem key selected, point to New on the
Edit menu, and then click String Value.

b. Type the name of the value that is missing from your registry as it is
listed in the table that is in step 5, and then press ENTER.

c. With the value from step 6b selected, click Modify on the Edit menu.

d. In the Value data box of the Edit String dialog box, type the value for
the missing string value.

e. Repeat steps 6a to 6d for each value that is missing from the table that
is in step 5.

7. On the File menu, click Exit.

For Office 2007:

---------------------------

The "E-mail" command is missing or is unavailable in Excel 2007, in
PowerPoint 2007, or in Word 2007

http://support.microsoft.com/kb/834008

Word 2007 Send as Email greyed out in Word Mail

http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.
public.word.mail&tid=013b92be-6daa-46f0-8030-dc1de1027edb&p=1

Step 3: Change the default e-mail program to Windows Mail

============================

To do this, close all the Office applications and follow these steps:

1. Start Microsoft Internet Explorer.  

2. On the Tools menu, click Internet Options.  

3. Click the Programs tab.  

4. Click Set Programs.  

5. Click Set your default programs.  

6. Highlight Outlook Express in the left panel, click on Set this program as
default.

Open a Word/Excel document to check this feature again.

Ditto.....MS Office 07 H&S ed. Greyed out e-mail button. I found that if you
save the data to desktop, you can right click it and send to mail
recipient....it will atttach and send in the active mail program, ie; Eudora
(my mail program), ect. I have no idea why it works this way and not
visa-versa.....  I have XP Pro OS. I do not use MS mail systems. If I attach
it with the attach button in Eudora it fails to send it in the correct
format. It is rediculus to operate this way.... David P