The current email restrictions were put in place because of a security issue with sendmail (https://github.com/go-gitea/gitea/pull/17688). Remove this restriction and instead ensure that this security issue cannot happen with sendmail.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7829
Reviewed-by: Ellen Εμιλία Άννα Zscheile <fogti@noreply.codeberg.org>
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: famfo <famfo@famfo.xyz>
Co-committed-by: famfo <famfo@famfo.xyz>