You can designate one or more text fields from your Contact Forms to be Email Address fields that are used for Email Messaging.
Makerble will use the email addresses that are designated as Email Address fields when
Sending email messages to contacts
and receiving email messages from contacts.
Steps
Only an Organisation Admin can designate text fields to be Email Address fields
Select My Apps in the top menu
Select Control Panel
Scroll down to Account section and select Preferences
The Activate Email Messaging tick box should already be ticked. If it is not ticked, do tick it.
In the next box, select the Contact Form fields you would like to designate as being the ones that hold the email address of your contacts. You can select multiple fields
Press Save.
Any contacts who have an email address in one of your designated fields, will now be available to receive emails when you are on the Create New Broadcast page