I am very thankful to jjzhuang who promptly responded to all my posts. One of the reply was having a reference to creating a persona in Zimbra desktop. I have the following questions on using persona ?

If I add a Persona to an account, that gives me one more email address to use in From field while sending messages. I will appreciate if the following doubts can be clarified.

a) Does adding a persona work exactly same as address guard addresses in yahoo.com web account (once I manually create all the address guard addresses from which I want to send emails) ?
b) Does the default options while creating a persona ensure that the reply to the mail sent from the persona comes back to the persona and not to the email to the main account address. I see additional fields that can be used while creating the persona for having a different reply-to email ?
c) When do I use the "Use this persona" fields ? What is the default behaviour if do not change anything except Persona Name and From fields.
d) Is the Persona attached to the same account or is available for all the accounts (e.g. If I have configured Zimbra for ymail.com as well as yahoo.com and add persona to yahoo account, does it affect ymail.com account in any way ?