mailto HTML e-mail link with dynamicly built subject

Hi need to build a subject dynamically. I.e. I have a input with some data which I want to add to subject.

For example if I just build html I can write the following:

<span style="color: #434343; font-family: 'Segoe UI REGULAR'; font-size: 12pt;">
   <text id="supportDescription">Id is '[context.eventId]' .</text>
 </span>

While opening html I'll see Id is 345 (345 is an argument) Instead of adding an id to the html, I want to add a mailto link including the id:

<a href="mailto:name@gmail.com?subject=The%20 reply for evetId '[context.eventId]'">Send mail </a>

Will the substation work here also. And the subject will be The reply for evetId 345