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Instead of playing with the ribbon which if you do succeed in removing / disabling the button would at best be a hack I suggest you do the following.<br />
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Have a Boolean set to False.<br />
&nbsp;<br />
Hook into the send event of an email and if the Boolean is false cancel the send and tell the user how to send the email properly.<br />
<br />
On your new send button set the Boolean to true and send.<br />
<br />
This will stop the use of the send button.
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Instead of playing with the ribbon which if you do succeed in removing / disabling the button would at best be a hack I suggest you do the following.

Have a Boolean set to False.
 
Hook into the send event of an email and if the Boolean is false cancel the send and tell the user how to send the email properly.

On your new send button set the Boolean to true and send.

This will stop the use of the send button.

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Is there a way to hide or disable the Send button in an Outlook message window? &nbsp;We have a replacement Send button (for email encryption) added to the ribbon but our users can't seem to break a 10+ year habit of using the default send button. &nbsp;Any suggestions?
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Is there a way to hide or disable the Send button in an Outlook message window?  We have a replacement Send button (for email encryption) added to the ribbon but our users can't seem to break a 10+ year habit of using the default send button.  Any suggestions?

Disable Send Button in Outlook 2010

Microsoft Outlook is a personal information manager from Microsoft, available as a part of the Microsoft Office suite. Although often used mainly as an email application, it also includes a calendar, task manager, contact manager, note-taker, journal, and web browser.