Invalid email address issue in my logged emails

Invalid email address issue in my logged emails

when I click on emails in my leads (emails that i have sent my leads via the BCC dropbox addie) I get the error message that "invalid email address found".....I can't open the emails within my lead details that haven been logged.  I used to be able to see them so maybe this is a recent issue that doesn't apply to older leads?  

Frustrating for follow to not see my previous emails/discussions.

Warm regards,

jay