fosstodon.org is one of the many independent Mastodon servers you can use to participate in the fediverse.
Fosstodon is an invite only Mastodon instance that is open to those who are interested in technology; particularly free & open source software.
If you wish to join, contact us for an invite.
@codemonkey I'm a protonmail user and pay...but if you want somthing similiar try @Tutanota . You will still have to pay if you have outgrown your free protonmail size limit.. but Tutanota is significantly cheaper.