Unreadable!

Please use <code>...</code> tags ... and please read Markup in the Monastery

Now, what you posted appears (XML view) to be intended to render this way:

I recently tried cleaning up following HTML and got problem. The end quote was missing on an attribute value.

use strict;
use warnings;
use HTML::Tidy;
my $html="<a href=\"mailto:test\@test.net><font size=4>Email Us</a>";
my $tidy = HTML::Tidy->new();
my $clean = $tidy->clean($html);
print "Clean HTML:\n---------------------------\n$clean\n";
[download]

This produced incorrect output.

So, what was the incorrect output? Please also read How do I post a question effectively?.

...and on the offchance you don't know what's wrong with your $html, check the quoting, the missing </font> tag, and the H::T docs.