OK, I was able to Scan to Email work with GMAIL, but it only works with when sending to a GMAIL account. Use aspmx.l.google.com as the SMTP Server. Use port 25. Under Authentication use "no Authentication. Now please remember this on the return Email address do not put in the email that you will be sending to or else the GMAIL server thinks it is SPAM and trashes it. This took me a while to figure out. Everything worked fined when I used my hotmail account in the "Return Email Address" and then scanned and emailled to my gmail account. I hope this helps!
