The system is as trustless as it can be.

As the system needs to send your messages after you are dead, it's impossible to encrypt it in a way that only you can access it. Thus, there's still one person you need to trust: The administrator of the site.
In the case of the main last-mail.org site, that would be me.

To make this a non-issue for paranoid people, I've opened up the source: Anyone with a bit of knowledge of web servers can host their own version of the code for private use (for themselves or family/friends).

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Your data is protected in a way that makes it very hard for people to snoop, though. (including me):

• All identifying data (mail addresses, messages, sender alias names) are stored encrypted using MCRYPT_RIJNDAEL_128 with a padded iv. The exact value of this is dependent on your own mail address and the server salt. This makes everything unreadable for anyone looking directly at the database.
• Everything is stored with the use of a salt: Decrypting anything is impossible without having access to the server as well as the database.
• The site can only be accessed through HTTPS

Thank you for your reply!

~W-M