From: Address Help
This address is added to all messages sent through your account. It is re-written into all submitted messages, so regardless of the email account you use to submit a post, your recipients will see this value on the From: field of the message they receive.
That also means that any replies which result from your mailing (including some automatic out-of-office replies) will go to this address.
This address has both a "Real Name" portion and an "Email Address" portion. In MS Outlook for example, recipients see only the Real Name unless/until they attempt to reply. Only then does Outlook show the email address to which the reply will be sent.
Be cautious about changing this header too frequently. If recipients have the Email Address in their contact list, it may help your messages avoid spam filtering. If you subsequently change the header, your subsequent messages *might* not get through.