A method, apparatus, and computer program product for transmitting an email message to multiple groups of recipients is disclosed herein. In selected embodiments, a method may include composing an email message including digitally encoded content and email addresses associated with a first group of intended recipients. The method may further include adding, in response to a user request, email addresses associated with a second group of intended recipients. The email message may then be sent to the first and second groups of intended recipients. The method may further include preventing the first group of intended recipients from determining the identities of the second group of intended recipients, and preventing the second group of intended recipients from determining the identities of the first group of intended recipients.