In mailto replace subject and body adding 20 instead space in all file php using notepad

Question

I do have a query... Each post or comment on my blog has a mailto field with the subject and content, but there is a blank space in between the words that I would like to change by 20 percent to improve the HTML validity. Every mailto has a unique subject and body, so I want to replace them all using notepad++ regex that only matches strings of this kind:

<A HREF="mailto:pippo@pluto.it?subject=Diario: Tanto per ridere un p&ograve;...&amp;body=Gentile visitatore, La informo che messaggi offensivi o volgari verranno scartati, buona prosecuzione." CLASS="hyperlink">Pippo Pluto</A>

<A HREF="mailto:topolino@paperino.it?subject=Diario: Dead Space e Dead Sapce 2&amp;body=Gentile visitatore, La informo che messaggi offensivi o volgari verranno scartati, buona prosecuzione." CLASS="hyperlink">Paolino Paperino</A>

As result I'd like to have:

<A HREF="mailto:picodepaperis@dysney.it?subject=Diario:%20Neutrini%20sfondano%20i%20300.000%20Km/s&amp;body=Gentile%20visitatore,%20La%20informo%20che%20messaggi%20offensivi%20o%20volgari%20verranno%20scartati,%20buona%20prosecuzione." CLASS="hyperlink">De Paperis Pico</A>

I want to use a regular expression in Notepad++ to process all of my 560 PHP files that have blank spaces.

I created a regex that only looks for the mailto string and ignores any blank spaces.

<A HREF=\"mailto:([^"]*)\" CLASS="hyperlink">

Can someone please help me with this?