Sendside supports the ability to designate multiple TO and CC recipients on a secure message.  The REPLY and REPLY ALL behavior differs somewhat, however, based on the type of message being sent.

Due to security considerations, the Sendside system does NOT allow non-authenticated users to REPLY to ALL recipients added to a message.  Users who view messages without having to login or register to create an account are non-authenticated users.  This send method allows recipients to receive and reply to messages without the need to first create an account or create an authentiated user session.

Secure Messages.  Reply and Reply All behavior works as normal.  Because all users are authenticated, all users can REPLY or REPLY to ALL recipients.

Challenge & Response Messages.  Although multiple recipients (TO and CC) can be designated when composing a message (in Outlook or via the Secure Web Portal) each Challenge and Response message is constructed separately for delivery to each individual recipient.  Although the message will indicate all of the recipients, each recipient can only REPLY directly to the sender.

No-Login Required.  This method works the same way as Challenge & Response Messages.  Users can REPLY but not REPLY to ALL users because they are unauthenticated.