What email service are you using?
I use gmail.com and haven't had any problem getting emails from FC (or anyone for that matter). But some email servers (yahoo and hotmail for example) will have a problem accepting some emails unless you have defined the sender as a trusted site.
When you go to your FC account page and click on "Email Address" on the upper left portion of the page, what do you see when they give you your current email address?
Is it letter perfect for your email address in the form of: youridentifier@emailserver.com (or .net)?
Easy enough to delete, add or transpose a letter/number/punctuation mark when you're typing something in.
(Don't put your email address in the forum -- you must check its accuracy against what you have/know to be correct.)
Do you have another email address? If you do, then test the accuracy of the email address on FC by doing a right click copy of the email address shown in the box and send yourself an email to that address from your second email address. (Paste the email address in To: emailaddress).
If it gets bounced back to you, then there is a problem with the email address that FC has. (ie it's spelled wrong/doesn't exist as shown)
If that works fine for you, but FC is getting bounce backs from your email server (ie you don't receive FC emails), then your email server is restricting your incoming mail (defining it as spam or dangerous, etc).
If you are using hotmail or yahoo, I suggest you set up a gmail email account. It's free. Once it is active, change your FC email address to your gmail account and use that for FC and any offers that you might be doing (and require an email address) on this site.
As I mentioned someone else solved the site acceptance problem by defining FC as a trusted site with their hotmail account. That solves the problem for emails from FC, but not from any advertisers that you might be completing offers for and who want to send you a confirming email.
If your email server is restricting incoming emails (for your and their security), you might not receive all emails from the advertiser unless you put them on your trusted list as well.
Hence, my suggestion to set up an gmail account. Gmail does not restrict incoming emails. They may put items in your spam file, but they don't bounce them back to the sender.
Gmail can be accessed online.
I don't use the online account (don't like it much).
Instead I bring it into my LiveMail account on my W7 laptop.
(Or Outlook Express if you use that)
Don't remember what I did to accomplish that, but if you can't figure it out, maybe someone else on the forum can help.
If everything works fine for you and you already have an gmail account for FC, then send in a Support ticket, explaining that you tried to update your email address, but the system would not accept your submission(s).
Then give them your correct email address and ask them to put it into the system for you.
And ask them why this problem first came up when you tried to cash out in February.