When trying to send form letters via email to hundreds of recipients using
Word's Merge to Email feature, an Outlook confirmation message pops up asking
me to confirm that it is ok to let another program (Word) send the email.  
This happens only when choosing plain text as the email format, and it
happens for each indivdual email and recipient.  There is also a delay of 5
seconds before the YES button is available.  Therefore, when sending 200,
there is a 5 second delay between each one and you have to click the YES
button to send each one.  This takes a considerable amount of time.  When
sending them in html format, this delay and confimation don't occur at all.  
It sends the letters one after the other without hesitation.  Using Office
XP.  It is important to send in plain text to avoid garbage characters that
appear in the header when receiving html messages as plain text.