Function mail_due 

fn mail_due(
    config: &Config,
    now: i64,
    last: i64,
    asleep: bool,
    paused: bool,
) -> bool

Whether mail is fetched at this step: at its rhythm, not while you sleep or pause unless the matrix of what reaches you tells some mail then (as usual, nothing is told then, your safe senders’ and Always through’s shown, not told; it comes when Sioul opens or after), and only when new mail is notified at all.