Systemli.org runs a so-called Paste-service. This enables you to publically file a text document and send the link to a friend. You can choose for how long the filed text is accessible (e.g. self-destruction after first reading, after 5 minutes….)
For this purpose we use the software PrivateBin, so the servers hosts (us) cannot read what content you file.
Of cause, like with all services, the transmission is encrypted.