A: First off, congratulations on your nuptials, or acceptance into the witness protection program. Second, there is no change for either of those things. What you will want to do is two things:
2. Create a new Mailbox for your new name. Renaming a Mailbox is not something you would do since people will continue to send to your old address for a while. You can create a new Mailbox in System Administration, in the Mailbox listing. After you create your new mailbox, you will want to update your contact card in MRSware with your new e-mail address. You will probably also want to send out some type of broadcast e-mail to let your customers know your new address. Don't forget you can also set a friendly name and reply address for your Mailbox -- right-click on the Mailbox in your E-mail Panel and select "Edit Options" -- which you will want to update if you had previously set it.
You also may need to go into "Tools" -> "Preferences", click on E-mail, and change the "Default Mailbox" to your new mailbox, which makes your new mailbox appear first in the E-mail Panel. After you give people a chance to get your new mailbox address and start using it, you can either delete the old mailbox or put an Out-of-Office type auto-reply on it to let people know you won't be checking it any longer. In the meantime, you will have access to both your old and new mailboxes in the E-mail Panel of MRSware.
If you decide to delete a mailbox, make sure that you have an Archive of it, or copy over any messages that you want to save... Deleting a Mailbox permanently deletes all messages in it.
Further Reading:
Creating a New MRSware Mailbox
E-mail Options