Phabricator:phabricator-config-215df72f910dd575/en

By default, this software generates unique reply-to addresses and sends a separate email to each recipient when you enable reply handling. This is more secure than using "From" to establish user identity, but can mean users may receive multiple emails when they are on mailing lists. Instead, you can use a single, non-unique reply to address and authenticate users based on the "From" address by setting this to 'true'. This trades away a little bit of security for convenience, but it's reasonable in many installs. Object interactions are still protected using hashes in the single public email address, so objects can not be replied to blindly.