Can't configurate IMAP Account... "It would already be configured"

Can't configurate IMAP Account... "It would already be configured"

Hello together,

I would like to configurate a IMAP Account in my Zoho CRM, but get the Info:

You cannot use this account because it has already been used for IMAP configuration. Please use a different account to continue...

But I haven't implement a IMAP- or POP-Account in the backend of the CRM. Even a company mail address.

Have you any idea?