Email bounced

[Switch_Realty2256]

I am receiving an undeliverable  notice. The email address is correct and has been used previously in Adobe Send for sign. 

If I try to re-enter the email address, it says the email address has already been used. 

How do I fix this? 

[Caroline35627534htd8]

I have the same issue, the recipient has made changes to their security, but I can't seem to resend the document from Adobe.  I initially thought I had typed the incorrect email, but I haven't, any ideas how to force the document through?