At this time there is not a way to email directly from the TX plan. The only methods at this time that would allow you email the tx plan proposal would be
1- To print it to PDF and attach the PDF file to the email
2 - Take a screenshot of the print preview, save that image and attach it to the email.
3- Print out the proposal, scan it back into the computer and attach that to the email.
This has been added as an enhancement/Change request for future releases.
As far as adding notes/comments to the print out, the only method right now is to use the Yellow sticky notes and when you attach it check the box for it to Print on items for patient "On Tx proposals."
In our office we use the CutePDF writer to avoid printing and scanning. This goes to the desktop and then it becomes an attachment in the email. If anyone else has another way to email that eliminates a few clicks that would be great, although we have found this to be the fastest way so far.