Resolved XPI file not compatible

Recently I found a Thunderbird extension "sender_verification_extension-0.9.0.5-tb.xpi ". When I tried to install it I got an error saying that the extension wasn't compatible with my Thunderbird version (3.0.5).
I found a site with a solution for that problem:
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solution
go to developer's web site download the latest version
modified install.rdf change the version : 3.0.0.* in 3.0.*
and install it .
it's working
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Now I got the source code from the developers website so I can change the entry in the mentioned install.rdf file; so far so good.
But then I don't know how to proceed: there's a cryptic sentence in the solution: "and install it ".
My question is now: can anyone help me explain HOW tot install it.
I suppose I have to recompile the source somehow te create an xpi file.

Thanks in advance

 

Try downloading it from https://addons.mozilla.org/en-US/thunderbird/addon/120016/

 

the link is:
https://addons.mozilla.org/en-US/thunderbird/addon/345/

 

thank you very much
apparently the install worked fine, now testing.
much appreciated.

 

How ?

 

sorry, I don't understand your question "How? ".
it just works with the link (https://addons.mozilla.org/en-US/thu.../addon/120016/ )you have sent.

 

Good.