Encryption of electronic messages may be automatically processed by a messaging system based on keywords or other attributes of the messages. In one example, if the message includes a predefined keyword, the messaging system may automatically encrypt the message for all recipients outside of a private network. In another example, the messaging system may automatically encrypt messages based on recipient address. Thus, if a recipient is on a list of addresses to which encryption applies, the message being sent to that particular recipient may be encrypted while a copy of the message being sent to other recipients not on the list might remain unencrypted.