String name = "mats";
  String at = "@";
  String domain = "matsemann";
  String tld = ".com";
  String email = name + at + domain + tld;

Some projects:

https://github.com/Matsemann/

https://news.ycombinator.com/item?id=7654141

https://news.ycombinator.com/item?id=10410813