This article explains the reason for the removal of the reply button on HES email encryption.
Starting March 1,2018, the ability to reply to an encrypted message generated from HES will be removed.
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This is due to a known issue regarding some non-HES users who are unable to send mails by using the reply function. Issues are known to be related to SPF Blocking and Geo-Fencing or blocking IP’s from certain sources.
HES email encryption will still be functional but will now be available only with a one way function. It will be available exclusively to HES subscribers. If replies must be encrypted, the sending/replying person must use his/her own encrypting application.