Members of a space can opt to have discussion messages also sent to them by email and to reply to those messages using their normal email client, such as Outlook.
Normally Jiglu will send out these messages with the same From:, To:, Cc: and Reply-To: headers as they arrived with. However, this means that if someone chooses Reply rather than Reply all when composing their reply then it will go to the writer of the email they are replying to, rather than back to the space for distribution to everyone.
While this behaviour may be preferred by some groups, others might prefer that everything goes to the group whatever reply option is chosen. To do this, in the space go to Settings, choose the Advanced settings tab and then the Email processing option. Change the Remove Reply-To: headers setting to Yes and the Add Reply-To: header also to Yes, and then select the Save button.