In the key you can use letters or numbers, separate numbers by spaces if they consist of more than 1 digit.
You can send just encoded message to your friend. To be able to read it he or she will need the key , which he or she should obtain in a different way e.g. by chat.
To send a message, fill in the following fields:
You need to enter a valid email address.
This field is required.
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Copy the content and give it to the recipient.