I use Horde web mail.
I attempted to send one of my customers an email only to find my address book was empty. I located his email address from a prior sent mail.
When I attempted to save his email address into my address book, a prompt came up stating "Invalid address book: 7cf686590370771c25021faad6a4c14c"
I'm not sure why? What would be my next step to resolve this issue?