High Security
The Swiss Post offers IncaMail with the security you need. The four letters in INCA stand for four security characteristics:

I as in Integrity
The message remains unchanged. Using a digital signature, IncaMail makes sure that your data remains unchanged through all transmission steps.

N as in Non-reputability
Sending and receiving are verifiable. Message pickups are secured and documented with IncaMail. With a Swiss Post Registered you also receive proof in the form of a digitally signed Post receipt with an officially recognized time stamp.

C as in Confidentiality
Your data cannot be viewed by outsider parties. IncaMail transfers all data over a protected SSL connection.

A as in Authentification
The recipient is unmistakably identified. For unmistakable identification, the recipient enters a PIN the first time he receives a message. The sender communicates the PIN directly by telephone, fax or text message.