Consider...

my %addrbook = $*IN.lines.map( { .split(/\s+/, 2) } );

for %addrbook.classify({ .value.substr(0,1).uc }).sort -> $g {
    say "{$g.key}:";
    .say for $g.value».invert».fmt("  %-32s %s");
}

...and we're done!