This solution came from one of our great TSEs, Anthony Watson, as a part of something he was working on with a customer.
Step 1: Create a custom vardef that points to the related record, as shown in previous post, HOWTO: Grab fields from a related record without Sugar Logic
Step 2: Add a ‘function’ entry to the above array that returns the email field html:
Save the above example as : custom/Extension/modules/Contacts/Ext/Vardefs/related_account_email.php
Notice that we are providing a path to a custom script that holds the function. While Sugar has a built-in function getEmailAddressWidget that returns the email field html, it expects the first parameter to be the bean object that you want to generate the email field from. As far as I can tell, there is not a way to force the vardef to pass the related bean object to the function, so we create an intermediary function to handle this:
Save the above as custom/getEmailAddressWidgetFromId.php to match the path value provided in the vardef.
After the above files are in place, do a Quick Repair & Rebuild and then move your new Account Email Address into the Display View layout via Studio. Note, you will likely see it as LBL_ACCOUNT_EMAIL until you update the label.