Lost smtp list and settings after update

Oh dear, this morning my wife told me that she was unable to send email from any of the gmail accounts she has (4) but she was able to receive.
Last night she downloaded and installed the 10.10.4 combi update.
I had a look at her Mail preferences
and found that the smtp outgoing server box had "none" in the menu, So I pulled up the list and low and behold there were none listed where previously she had 6.
I booted her MBP up from her CCC backup (10.10.3) and Mail worked for both send and receive.
So I copied the account details from the CCC version into Mail on the 10.10.4 version but no change.
I'm not sure how I can restore the necessary files from the backup without doing a full restore.
I considered deleting all of her email accounts and re entering them, seems like a lot of work especially as my wife tells me she is not sure of the password for 2 of them AND she has two step verification on her primary account.

I have spent 3 hours on this today with no luck at all.

Any help would be much appreciated.

Might be some work involved, but I would restore her CCC backup and then download the 10.10.4 combo update and try again. Otherwise you may be fighting windmills for hours before you can resolve it.

If the ONLY problem is that you don't have SMTP servers for the GMail accounts, they all use the EXACT SAME smtp address, which is smtp.google.com.

So just enter that in your accounts.