Maybe send a confirmation link to the new address, that they need to click on before before it is changed.  I get irritated with two the field thing. I use software that auto fills my correct email. If typing is enforced, I tend to make a mistake. Sometimes the second field will not permit the software to autofill. That said, a second field would catch a number of people typing it incorrectly into one. 
By sending a confirmation change link to the new email address, if the wrong email was entered, then no change would be made. If they verified with a link that required them to log in then the changed email would stand. 

I do very much the suggestion to put up some confirmation notice before the changed email is committed. 
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Sandi Dickenson
ASG Volunteers Group.