Check your mail for all your accounts from a unified interface. This includes not only your Zoho account, but your existing POP accounts as well.
Enable users to alter the 'From' email ids while sending messages from their personal accounts in sync with the situation and recipient. A one time authentication ensures validity of the other email ids that appear as drop-down options on the 'From' section of the message editor.
Specify email signatures and vacation responders on a per account basis. Vacation responses are configurable at the account level, which lets you control which of your contacts will be informed that you're away.