Get Routing Email Address via Post Custom Field

Yes this is possible if the form is embedded in the post containing the custom field data.

- Add an Email field to your form

- Edit this Email field and give it a Field Label of "Send To Email" or whatever you want to call it

- Select the Advanced tab and make the field visibility so it is Admin Only

- On the Advanced tab set the default value for that field to use the {custom_field} merge tag and pass it the name/key of the custom field you want to get the value from. If the custom field name is email then you would use {custom_field:email}

- See this screenshot as an example: http://i.imgur.com/3Gr6T.png

- Save your form

- Edit your notificiations

- On the Send To address for the Admin Notification you will use the merge tag for the email field you created. You can get it using the "Insert form field" drop down above the Message body to insert it into the Message and then just copy-n-paste it into the Send To field.

- See this screenshot as an example, your merge tag will be different as it's dynamic: http://i.imgur.com/V10sf.png

- Save notifications

- Embed it on the post

Now that email field is going to be hidden and it's going to be populated with the value of the custom field you tell it to use. Notifications are then going to send to that address.