Invalid certificate for IMAP

Invalid certificate for IMAP

From Postbox:

"An error occurred during a connection to imap.zoho.com:993.

You have received an invalid certificate.  Please contact the server administrator or email correspondent and give them the following information:

Your certificate contains the same serial number as another certificate issued by the certificate authority.  Please get a new certificate containing a unique serial number.

(Error code: sec_error_reused_issuer_and_serial)"

A quick Google search shows this has happened before, but nothing recently. Hopefully it will be fixed soon!