I recently upgraded to the latest version of DT Register. Now for some reason after a user registers for an event and the Thank you page comes up there is a message in red that states "Could not instantiate mail function."
In the DT Registers Configuration under the emails tab I have the From Name and From Email filled out properly so I am not sure what is going on here. These from fields contain the same info as found in the global Joomla mail config.
Modified the options for fields firstname, lastname and email. Now, to avoid incorrect setup problems, you can not unpublish or delete the default "email" field, nor can you make it not required. The firstname and lastname fields can be unpublished, but not deleted.
Maybe when this was attempted during the upgrade it failed and I was left with none of these fields (the rest of our 80 plus fields are fine though)