Mechanism processing secure messages

Secure messages including encrypted and digitally signed messages are fragile in terms of modifications applied to their body. As a result, some of the actions performed on these messages can either damage the encryption or invalidate a digital sign. However, CodeTwo Exchange Rules is equipped with the secure messages processing mechanism that lets you process actions (Apply full message composition, Insert disclaimer and Insert signature) for both above mentioned types of secure messages keeping them encrypted and valid.


Be aware that not all encryption and digital signatures standards are supported - see Supported platforms and requirements article.

If you, however, use an encryption technology that is applied ‘on the way’ between sender and recipient, you can configure mail flow rules in your Exchange Server, so that a chosen action (e.g. Insert a signature) is applied before a message is secured (encrypted / digitally signed). In this case, the email signature will be added to messages that haven’t been secured yet.


Note that the program processes both types of secure messages by default. It means that if the conditions set in rules are met then both types of these messages will be processed by the program yet have the applicable actions applied. However, you can exclude either of the secure messages' types from processing by choosing the Secure message type on the Exceptions tab in your rules. On the other hand, if you want to instruct the program to execute actions set in rules only on secure messages (excluding other types of messages such as new emails, replies, etc.), go to the Conditions tab in these rules and configure the Secure message type condition.

The mechanism responsible for processing secure messages works in the following way:

  1. First, it creates the envelopes as actions cannot be executed within original messages.
  2. The original sender, recipient(s) and subject properties from secure messages are being copied to the envelopes.
  3. All requested actions are being executed on the envelopes.
  4. Last but not least, the mechanism adds secure messages to the envelopes as attachments.
  5. After that, the envelopes including attached secure messages are sent.


The envelope message content can be customized using the editor available in program’s settings (the Secure messages tab). Thanks to that, you can for example add the signature, which you intended to put into the secure message, to the envelope message instead as a fallback.

Learn how to adjust the template of envelopes

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