Confidential data should preferably be transferred to and from Jonas Ranstam using the secure shell (SSH) at ssh.ranstam.se. A user identity and a password are required.
As long as the content is encrypted, data sets and documents can also be sent via email. GPG provides reliable encryption. The public key for email@example.com can be found here. Protonmail offers a reliable and convenient solution to automatic encryption with GPG. The email addresses firstname.lastname@example.org and email@example.com can be used for this purpose.