use Encode qw(decode);

my $str = 'username, A Ne=?UTF-16?B?dwAgAEMAcgBlAGQAaQB0ACAAQwBhAHIAZAAgAEMAbwB1AGwAZAAgAEIAZQAgAEgAZQBhAGQAZQBkACAAWQBvAHUAcgAgAFcAYQB5AA==?=';

my $chr = decode('MIME-Header', $str);

print "$chr\n";

##</code><code>##

UTF-16:Unrecognised BOM 7700 at /.../Encode/MIME/Header.pm line 81.

##</code><code>##

use MIME::Base64;

my $cstr = 'dwAgAEMAcgBlAGQAaQB0ACAAQwBhAHIAZAAgAEMAbwB1AGwAZAAgAEIAZQAgAEgAZQBhAGQAZQBkACAAWQBvAHUAcgAgAFcAYQB5AA';

my $chk = decode_base64($cstr);
print "$chk\n";

##</code><code>##

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