4.8 Support for signed emails
MetaDefender Email Gateway Security gives you an option to skip the modification of emails which are digitally signed so the signature can remain valid after MetaDefender Email Gateway Security processed the email. This behavior is enabled by default. To disable it per rule please check the Advanced scan settings section in 4.2 Security rules.
If an email was signed/encrypted you will see a key icon ( 
) in the Email History next to the recipients.
Modification rules for signed emails
Email content was blocked
Due to security reasons if there is a blocked content in a signed email MetaDefender Email Gateway Security will either block the whole email or modify its content depending on what action is selected for the blocked emails in 4.2 Security rules. If the selected action is to delete blocked contents then the blocked contents will be removed and (if configured) disclaimer will be added to the email. If the selected action is to deliver blocked contents then the contents will be delivered but disclaimer won't be added to the email. When the selected action is to block emails then modifying the email is irrelevant.
Email content was sanitized
When a signed email has a content which gets sanitized by MetaDefender Core then MetaDefender Email Gateway Security won't replace the original content with its sanitized counterpart and won't add disclaimer to the email. If a sanitization failure occurs during processing a signed email the email won't get blocked as it normally would.
Any attachment which were blocked and sanitized will be removed regardless of other settings.
Email content was allowed
MetaDefender Email Gateway Security won't add disclaimer to the email and the content won't be modified.
Email was bypassed
MetaDefender Email Gateway Security won't add disclaimer to the email and the content won't be modified.
Adding extra headers to the email
Since adding extra headers to the email won't break the signature you can safely configure security rules to add specific headers to the emails if you would like to do that.