If/Then Formula Statement - How to display an updated/corrected email address?

Hi folks,

I have a table of data that is being populated by Sync'd data - so it's not editable once it's sync'd to Quickbase.  However, people sometimes make errors and I need a way to correct their email addresses if they have made a typo.

What I thought I would do is add a checkbox field that indicates the original email is invalid.  Then an email address field that can be edited, that will appear if you check the box that the first entry is invalid, and then I wanted to create a final formula-email address field that is populated with which ever of those two fields is correct.  

So - I was thinking an If / Then statement would work well.  
If the 'invalid' checkbox IsNull/unchecked, then field shows the original/source field.  If the 'invalid' checkbox = "yes" or is checked, then display the corrected email address.

I've tried several formulations, but I keep getting stuck. Not quite sure why I'm doing wrong here.  I currently have written:

//If([Incorrect or invalid email address.]="no", [Ticket Holder Email Address])
//If([Incorrect or invalid email address.]="yes", [Corrected Email Address])

Ideas on what I've missed here?

Thank you!

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Jennifer Juhasz
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