I made "Leave a message" form send email using the same code that handles our contact form page. This means that since our contact form already send email, I can use the same code for the "Leave a message" form. 
I made a copy of docontact.php and saved it under mibew directory  (i.e the same location as leavemessage.php), 
webim/I went to 
leavemessage.tpl  from syle/default/template/ (under my mibew settings from admin dashboard, i chose default )
I changed the form action under  leavemessage.tpl  
from ${mibewroot}/leavemessage.php to ${mibewroot}/docontact.php (remember, docontac.php is the php page that handles our website's contact form submission)
I ensured that the names of the form fields in leavemessage.tpl 
matched the name of the posted form fields in the docontact.php 
e.g in leavemessage.tpl, name field=name, email field = email, message field=message
      in docontact.php, name=$_POST['name'], email=$_POST['email'], message=$_POST['message']
Very happy with the result. Hope this helps someone like other mibew tips helped me 
